DRAM: Architectures, Interfaces, and Systems A Tutorialblj/talks/DRAM-Tutorial-isca2002-2.pdf ·...
Transcript of DRAM: Architectures, Interfaces, and Systems A Tutorialblj/talks/DRAM-Tutorial-isca2002-2.pdf ·...
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
DR
AM
: why
bot
her?
(i m
ean,
be
side
s th
e “m
emor
y w
all”
thin
g? ..
. is
it ju
st a
per
form
ance
is
sue?
)
thin
k ab
out e
mbe
dded
sys
tem
s:
thin
k ce
llpho
nes,
thin
k pr
inte
rs,
thin
k sw
itche
s ...
nea
rly e
very
em
bedd
ed p
rodu
ct th
at u
sed
to
be e
xpen
sive
is n
ow c
heap
. w
hy?
for o
ne th
ing,
rapi
d tu
rnov
er fr
om
high
per
form
ance
to
obso
lesc
ence
gua
rant
ees
gene
rous
sup
ply
of C
HE
AP,
H
IGH
-PE
RF
OR
MA
NC
E
embe
dded
pro
cess
ors
to s
uit
near
ly a
ny d
esig
n ne
ed.
wha
t doe
s th
e “m
emor
y w
all”
mea
n in
this
con
text
? pe
rhap
s it
will
take
long
er fo
r a
high
-pe
rfor
man
ce d
esig
n to
bec
ome
obso
lete
?
DR
AM
: Arc
hit
ectu
res,
In
terf
aces
, an
d S
yste
ms
A T
uto
rial
Bru
ce J
aco
b a
nd
Dav
id W
ang
Ele
ctri
cal &
Co
mp
ute
r E
ng
inee
rin
g D
ept.
Un
iver
sity
of
Mar
ylan
d a
t C
olle
ge
Par
k
http://www.ece.umd.edu/~blj/DRAM/
UN
IVE
RS
ITY
OF
MA
RY
LAN
D
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
NO
TE
Ou
tlin
e
•
Bas
ics
•
DR
AM
Evo
luti
on
:
Str
uct
ura
l Pat
h
•
Ad
van
ced
Bas
ics
•
DR
AM
Evo
luti
on
:
Inte
rfac
e P
ath
•
Fu
ture
Inte
rfac
e Tr
end
s &
Res
earc
h A
reas
•
Per
form
ance
Mo
del
ing
:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
Bre
ak a
t 10
a.m
. — S
top
us
or
star
ve
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
first
off
-- w
hat i
s D
RA
M?
an
arra
y of
sto
rage
ele
men
ts
(cap
acito
r-tr
ansi
stor
pai
rs)
“DR
AM
” is
an a
cron
ym (
expl
ain)
w
hy “
dyna
mic
”?
- ca
paci
tors
are
not
per
fect
...
need
rec
harg
ing
- ve
ry d
ense
par
ts; v
ery
smal
l; ca
pact
iros
have
ver
y lit
tle
char
ge ..
. thu
s, th
e bi
t lin
es a
re
char
ged
up to
1/2
vol
tage
leve
l an
d th
e ss
ense
am
ps d
etec
t the
m
inut
e ch
ange
on
the
lines
, the
n re
cove
r th
e fu
ll si
gnal
Bas
ics
DR
AM
OR
GA
NIZ
AT
ION
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Sto
rag
e el
emen
t
Sw
itch
ing
el
emen
t
Bit
Lin
e
Wo
rd L
ine
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
(cap
acit
or)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
so h
ow d
o yo
u in
tera
ct w
ith th
is
thin
g? le
t’s lo
ok a
t a tr
aditi
onal
or
gani
zatio
n fir
st ..
. CP
U
conn
ects
to a
mem
ory
cont
rolle
r th
at c
onne
cts
to th
e D
RA
M it
self.
let’s
look
at a
rea
d op
erat
ion
Bas
ics
BU
S T
RA
NS
MIS
SIO
N
BU
SM
EM
OR
YC
ON
TR
OL
LE
RC
PU
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
at th
is p
oint
, all
but l
ines
are
attt
th
e 1/
2 vo
ltage
leve
l.
the
read
dis
char
ges
the
capa
cito
rs o
nto
the
bit l
ines
...
this
pul
ls th
e lin
es ju
st a
littl
e bi
t hi
gh o
r a
little
bit
low
; the
sen
se
amps
det
ect t
he c
hang
e an
d re
cove
r th
e fu
ll si
gnal
the
read
is d
estr
uctiv
e --
the
capa
cito
rs h
ave
been
di
scha
rged
... h
owev
er, w
hen
the
sens
e am
ps p
ull t
he li
nes
to
the
full
logi
c-le
vel (
eith
er h
igh
or
low
), th
e tr
ansi
stor
s ar
e ke
pt
open
and
so
allo
w th
eir a
ttach
ed
capa
cito
rs to
bec
ome
rech
arge
d(if
they
hol
d a
‘1’ v
alue
)
Bas
ics
[PR
EC
HA
RG
E a
nd
] R
OW
AC
CE
SS
AK
A: O
PE
N a
DR
AM
Pag
e/R
ow
RA
S (
Ro
w A
dd
ress
Str
ob
e)
or
or
AC
T (
Act
ivat
e a
DR
AM
Pag
e/R
ow
)
BU
SM
EM
OR
YC
ON
TR
OL
LE
RC
PU
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
once
the
data
is v
alid
on
ALL
of
the
bit l
ines
, you
can
sel
ect a
su
bset
of t
he b
its a
nd s
end
them
to
the
outp
ut b
uffe
rs ..
. CA
S
pick
s on
e of
the
bits
big
poin
t: ca
nnot
do
anot
her
RA
S o
r pr
echa
rge
of th
e lin
es
until
fini
shed
read
ing
the
colu
mn
data
... c
an’t
chan
ge th
e va
lues
on
the
bit l
ines
or
the
outp
ut o
f th
e se
nse
amps
unt
il it
has
been
re
ad b
y th
e m
emor
y co
ntro
ller
Bas
ics
CO
LU
MN
AC
CE
SS
RE
AD
Co
mm
and
or
CA
S: C
olu
mn
Ad
dre
ss S
tro
be
BU
SM
EM
OR
YC
ON
TR
OL
LE
RC
PU
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
then
the
data
is v
alid
on
the
data
bu
s ...
dep
endi
ng o
n w
hat y
ou
are
usin
g fo
r in
/out
buf
fers
, you
m
ight
be
able
to o
verla
p a
litttl
e or
a lo
t of t
he d
ata
tran
sfer
with
th
e ne
xt C
AS
to th
e sa
me
page
(t
his
is P
AG
E M
OD
E)
Bas
ics
DA
TA T
RA
NS
FE
R
no
te: p
age
mo
de
enab
les
over
lap
wit
h C
AS
BU
SM
EM
OR
YC
ON
TR
OL
LE
RC
PU
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
... w
ith
op
tio
nal
ad
dit
ion
alC
AS
: Co
lum
n A
dd
ress
Str
ob
e
Dat
a O
ut
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
NO
TE
Bas
ics
BU
S T
RA
NS
MIS
SIO
N
BU
SM
EM
OR
YC
ON
TR
OL
LE
RC
PU
... B
it L
ines
...
Mem
ory
Arr
ay
Row Decoder
. .. Word Lines ...
DR
AM
Dat
a In
/Ou
tB
uff
ers
Sen
se A
mp
s
Co
lum
n D
eco
der
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
DR
AM
“la
tenc
y” is
n’t
dete
rmin
istic
bec
ause
of C
AS
or
RA
S+
CA
S, a
nd th
ere
may
be
sign
ifica
nt q
ueui
ng d
elay
s w
ithin
th
e C
PU
and
the
mem
ory
cont
rolle
rE
ach
tran
sact
ion
has
som
e ov
erhe
ad. S
ome
type
s of
ov
erhe
ad c
anno
t be
pipe
lined
. T
his
mea
ns th
at in
gen
eral
, lo
nger
bur
sts
are
mor
e ef
ficie
nt.
Bas
ics
B
CD
DR
AM
E2/
E3
E1
F
A
CP
UM
emC
ontr
olle
r
A: T
rans
actio
n re
ques
t may
be
dela
yed
in Q
ueue
B: T
rans
actio
n re
ques
t sen
t to
Mem
ory
Con
trol
ler
C: T
rans
actio
n co
nver
ted
to C
omm
and
Seq
uenc
es(m
ay b
e qu
eued
)D
: Com
man
d/s
Sen
t to
DR
AM
E1:
Req
uire
s on
ly a
CA
S o
rE
2: R
equi
res
RA
S +
CA
S o
r
F: T
rans
actio
n se
nt b
ack
to C
PU
“DR
AM
Lat
ency
” = A
+ B
+ C
+ D
+ E
+ F
E3:
Req
uire
s P
RE
+ R
AS
+ C
AS
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
NO
TE
Bas
ics
PH
YS
ICA
L O
RG
AN
IZA
TIO
N
Th
is is
per
ban
k …
Typ
ical
DR
AM
s h
ave
2+ b
anks
x2 D
RA
Mx4
DR
AM
x8 D
RA
M
... B
it L
ines
...
Sen
se A
mp
s
. . . .
Dat
aB
uff
ers
x8 D
RA
M
Row Decoder
Mem
ory
Arr
ay
Co
lum
n D
eco
der
... B
it L
ines
...
Sen
se A
mp
s
. . . .
Dat
aB
uff
ers
x2 D
RA
M
Row Decoder
Mem
ory
Arr
ay
Co
lum
n D
eco
der
... B
it L
ines
...
Sen
se A
mp
s
. . . .
Dat
aB
uff
ers
x4 D
RA
M
Row Decoder
Mem
ory
Arr
ay
Co
lum
n D
eco
der
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
let’s
look
at t
he in
terf
ace
anot
her
way
.. th
e sa
y th
e da
ta s
heet
s po
rtra
y it.
[exp
lain
]
mai
n po
int:
the
RA
S\ a
nd C
AS
\ si
gnal
s di
rect
ly c
ontr
ol th
e la
tche
s th
at h
old
the
row
and
co
lum
n ad
dres
ses
...
Bas
ics
Rea
d T
imin
g fo
r C
onv
enti
on
al D
RA
M
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
RA
S
CA
S
Ad
dre
ss
DQ
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
sinc
e D
RA
M’s
ince
ptio
n, th
ere
have
bee
n a
stre
am o
f cha
nges
to
the
desi
gn, f
rom
FP
M to
ED
O
to B
urst
ED
O to
SD
RA
M. t
he
chan
ges
are
larg
ely
stru
ctur
al
mod
ifica
tions
--
nim
or -
- th
at
targ
et T
HR
OU
GH
PU
T.
[dis
cuss
FP
M u
p to
SD
RA
M
Eve
ryth
ing
up to
and
incl
udin
g S
DR
AM
has
bee
n re
lativ
ely
inex
pens
ive,
esp
ecia
lly w
hen
cons
ider
ing
the
pay-
off (
FP
M
was
ess
entia
lly fr
ee, E
DO
cos
t a
latc
h, P
BE
DO
cos
t a c
ount
er,
SD
RA
M c
ost a
slig
ht r
e-de
sign
). ho
wev
er, w
e’re
run
out
of “
free
” id
eas,
and
now
all
chan
ges
are
cons
ider
ed e
xpen
sive
... t
hus
ther
e is
no
cons
ensu
s on
new
di
rect
ions
and
myr
iad
of c
hoic
es
has
appe
ared
[ do
LAT
EN
CY
mod
s st
artin
g w
ith E
SD
RA
M ..
. and
then
the
INT
ER
FAC
E m
ods
]
DR
AM
Evo
luti
on
ary
Tree
(Mo
stly
) S
tru
ctu
ral M
od
ific
atio
ns
Inte
rfac
e M
od
ific
atio
ns
Str
uct
ura
l
Co
nve
nti
on
al
FP
ME
DO
ES
DR
AM
Ram
bu
s, D
DR
/2F
utu
re T
ren
ds
. . . . . . . .
. . .
. . .
MO
SY
S
FC
RA
M
VC
DR
AM$
Mo
dif
icat
ion
sTa
rget
ing
Lat
ency
Targ
etin
g T
hro
ug
hp
ut
Targ
etin
g T
hro
ug
hp
ut
DR
AM
SD
RA
MP
/BE
DO
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r C
onv
enti
on
al D
RA
M
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
RA
S
CA
S
Ad
dre
ss
DQ
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
FP
M a
allo
ws
you
to k
eep
th
esen
se a
mps
act
uve
for
mul
tiple
C
AS
com
man
ds ..
.
muc
h be
tter
thro
ughp
ut
prob
lem
: can
not l
atch
a n
ew
valu
e in
the
colu
mn
addr
ess
buffe
r un
til th
e re
ad-o
ut o
f the
da
ta is
com
plet
e
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r Fa
st P
age
Mo
de
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
Co
lum
nA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
Val
idD
atao
ut
RA
S
CA
S
Ad
dre
ss
DQ
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
solu
tion
to th
at p
robl
em -
- in
stea
d of
sim
ple
tri-s
tate
bu
ffers
, use
a la
tch
as w
ell.
by p
uttin
g a
latc
h af
ter
the
colu
mn
mux
, the
nex
t col
umn
addr
ess
com
man
d ca
n be
gin
soon
er
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r E
xten
ded
Dat
a O
ut
Ro
wA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
RA
S
CA
S
Ad
dre
ss
DQ
Co
lum
nA
dd
ress
Co
lum
nA
dd
ress
Val
idD
atao
ut
Val
idD
atao
ut
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
by d
rivin
g th
e co
l-add
r lat
ch fr
om
an in
tern
al c
ount
er r
athe
r th
an
an e
xter
nal s
igna
l, th
e m
inim
um
cycl
e tim
e fo
r dr
ivin
g th
e ou
tput
bu
s w
as r
educ
ed b
y ro
ughl
y 30
%
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r B
urs
t E
DO
Ro
wA
dd
ress
Co
lum
nA
dd
ress
RA
S
CA
S
Ad
dre
ss
DQ
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
“pip
elin
e” r
efer
s to
the
setti
ng u
p of
the
read
pip
elin
e ...
firs
t CA
S\
togg
le la
tche
s th
e co
lum
n ad
dres
s, a
ll fo
llow
ing
CA
S\
togg
les
driv
e da
ta o
ut o
nto
the
bus.
ther
efor
e da
ta s
tops
com
ing
whe
n th
e m
emor
y co
ntro
ller
stop
s to
gglin
g C
AS
\
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r P
ipel
ine
Bu
rst
ED
O
Ro
wA
dd
ress
Co
lum
nA
dd
ress
RA
S
CA
S
Ad
dre
ss
DQ
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
mai
n be
nefit
: fre
es u
p th
e C
PU
or
mem
ory
cont
rolle
r fr
om
havi
ng to
con
trol
the
DR
AM
’s
inte
rnal
latc
hes
dire
ctly
... t
he
cont
rolle
r/C
PU
can
go
off a
nd d
o ot
her
thin
gs d
urin
g th
e id
le
cycl
es in
stea
d of
“w
ait”
... e
ven
thou
gh th
e tim
e-to
-firs
t-w
ord
late
ncy
actu
ally
get
s w
orse
, the
sc
hem
e in
crea
ses
syst
em
thro
ughp
ut
DR
AM
Evo
luti
on
Rea
d T
imin
g fo
r S
ynch
ron
ou
s D
RA
M
(RA
S +
CA
S +
OE
... =
= C
om
man
d B
us)
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
D
RA
S
CA
S
Dat
a Tr
ansf
er
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
outp
ut la
tch
on E
DO
allo
wed
you
to
sta
rt C
AS
soo
ner
for
next
ac
cess
s (t
o sa
me
row
)
latc
h w
hole
row
in E
SD
RA
M -
- al
low
s yo
u to
sta
rt p
rech
arge
&
RA
S s
oone
r fo
r th
ee n
ext p
age
acce
ss -
- H
IDE
TH
E
PR
EC
HA
RG
E O
VE
RH
EA
D.
DR
AM
Evo
luti
on
Inte
r-R
ow
Rea
d T
imin
g fo
r E
SD
RA
M
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
D
Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
DP
RE
Reg
ula
r C
AS
-2 S
DR
AM
, R/R
to
sam
e b
ank
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
D
Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
D
ES
DR
AM
, R/R
to
sam
e b
ank
PR
E
Ban
k
Ban
k
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
neat
feat
ure
of th
is ty
pe o
f bu
fferin
g: w
rite-
arou
nd
DR
AM
Evo
luti
on
Wri
te-A
rou
nd
in E
SD
RA
M
(can
sec
on
d R
EA
D b
e th
is a
gg
ress
ive?
)
Com
man
d
Addr
ess
DQCloc
k
Row
Addr
Col
Addr
Valid
Data
Valid
Data
Valid
Data
Valid
Data
ACT
READ
Row
Addr
Col
Addr
Valid
Data
Valid
Data
Valid
Data
Valid
Data
ACT
WRI
TEPR
E
Reg
ula
r C
AS
-2 S
DR
AM
, R/W
/R t
o s
ame
ban
k, r
ow
s 0/
1/0
Com
man
d
Addr
ess
DQCloc
k
Row
Addr
Col
Addr
Valid
Data
Valid
Data
Valid
Data
Valid
Data
ACT
READ
Row
Addr
Col
Addr
Valid
Data
Valid
Data
Valid
Data
Valid
Data
ACT
WRI
TE
ES
DR
AM
, R/W
/R t
o s
ame
ban
k, r
ow
s 0/
1/0
PRE
Bank
Bank
Row
Addr
Col
Addr
Valid
Data
Valid
Data
Valid
Data
ACT
READ
PRE
Bank
Col
Addr
Valid
Data
Valid
Data
Valid
Data
Valid
Data
READ
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
mai
n th
ing
... it
is li
ke h
avin
g a
bunc
h of
ope
n ro
w b
uffe
rs (
a la
ra
mbu
s), b
ut th
e pr
oble
m is
that
yo
u m
ust d
eal w
ith th
e ca
che
dire
ctly
(m
ove
into
and
out
of i
t),
not t
he D
RA
M b
anks
... a
dds
an
extr
a co
uple
of c
ycle
s of
late
ncy
... h
owev
er, y
ou g
et g
ood
band
wid
th if
the
data
you
wan
t is
cach
e, a
nd y
ou c
an “
pref
etch
” in
to c
ache
ahe
ad o
f whe
n yo
u w
ant i
t ...
orig
inal
ly ta
rget
ted
at
redu
cing
late
ncy,
now
that
S
DR
AM
is C
AS
-2 a
nd R
CD
-2,
this
mak
e se
nse
only
in a
th
roug
hput
way
DR
AM
Evo
luti
on
Inte
rnal
Str
uct
ure
of V
irtu
al C
han
nel
Seg
men
t ca
che
is s
oft
war
e-m
anag
ed, r
edu
ces
ener
gy
$
Ro
w D
eco
der
2Kb
Seg
men
t
2Kb
Seg
men
t
2Kb
Seg
men
t
2Kb
Seg
men
t
Ban
k A
Ban
k B
16 C
han
nel
s
Inp
ut/
Ou
tpu
tB
uff
er
DQ
s
Sel
/Dec
(seg
men
ts)
Sen
seA
mp
s
2Kb
it#
DQ
s
Act
ivat
eP
refe
tch
Res
tore
Rea
dW
rite
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
FC
RA
M o
pts
to b
reak
up
the
data
arr
ay ..
onl
y ac
tivat
e a
port
ion
of th
e w
ord
line
8K r
ows
requ
ires
13 b
its tt
o se
lect
... F
CR
AM
use
s 15
(a
ssum
ing
the
arra
y is
8k
x 1k
...
the
data
she
et d
oes
not s
peci
fy)
DR
AM
Evo
luti
on
Inte
rnal
Str
uct
ure
of
Fast
Cyc
le R
AM
Red
uce
s ac
cess
tim
e an
d e
ner
gy/
acce
ss
t RC
D =
15n
st R
CD
= 5
ns
8M A
rray
13 b
its
Sen
se A
mp
s
8M A
rray
15 b
its
Sen
se A
mp
s
SD
RA
MF
CR
AM
(on
e cl
ock
)(t
wo
clo
cks)
Row Decoder
Row Decoder
(8K
r x
1Kb
)(?
)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
MoS
ys ta
kes
this
one
ste
p fu
rthe
r ...
DR
AM
with
an
SR
AM
in
terf
ace
& s
peed
but
DR
AM
en
ergy
[phy
sica
l par
titio
ning
: 72
bank
s]
auto
ref
resh
--
how
to d
o th
is
tran
spar
ently
? th
e lo
gic
mov
es
tthro
ugh
the
arra
ys, r
efre
shin
g th
em w
hen
not a
ctiv
e.
but w
hat i
s on
e ba
nk g
ets
repe
ated
acc
ess
for
a lo
ng
dura
tion?
all
othe
r ba
nks
will
be
refr
eshe
d, b
ut th
at o
ne w
ill n
ot.
solu
tion:
they
hav
e a
bank
-siz
ed
CA
CH
E o
f lin
es ..
. in
theo
ry,
shou
ld n
ever
hav
e a
prob
lem
(m
agic
)
DR
AM
Evo
luti
on
Inte
rnal
Str
uct
ure
of
Mo
Sys
1T-
SR
AM
. . . . . . . .
. . .
. . .
add
r
Ban
kS
elec
t
DQ
s
$
Au
toR
efre
sh
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
here
’s a
n id
ea o
f how
the
desi
gns
com
pare
...
bus
spee
d =
= C
AS
-to-
CA
S
RA
S-C
AS
==
tim
e to
rea
d da
ta
from
cap
acito
rs in
to s
ense
am
ps
RA
S-D
Q =
= R
AS
to v
alid
dat
a
DR
AM
Evo
luti
on
Co
mp
aris
on
of
Lo
w-L
aten
cy D
RA
M C
ore
s
DR
AM
Typ
eD
ata
Bu
s S
pee
dB
us
Wid
th
(per
ch
ip)
Pea
k B
W
(per
Ch
ip)
RA
S–C
AS
(tR
CD
)R
AS
–DQ
(t
RA
C)
PC
133
SD
RA
M13
316
266
MB
/s15
ns
30 n
s
VC
DR
AM
133
1626
6 M
B/s
30 n
s45
ns
FC
RA
M20
0 *
216
800
MB
/s5
ns22
ns
1T-S
RA
M20
0 32
800
MB
/s—
10 n
s
DD
R 2
66
133
* 2
1653
2 M
B/s
20 n
s45
ns
DR
DR
AM
40
0 *
216
1.6
GB
/s22
.5 n
s60
ns
RL
DR
AM
300
* 2
322.
4 G
B/s
???
25 n
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ou
tlin
e
•B
asic
s
•D
RA
M E
volu
tio
n: S
tru
ctu
ral P
ath
•A
dva
nce
d B
asic
s •
Mem
ory
Sys
tem
Det
ails
(L
ots
)
•D
RA
M E
volu
tio
n: I
nte
rfac
e P
ath
•F
utu
re In
terf
ace
Tren
ds
& R
esea
rch
Are
as
•P
erfo
rman
ce M
od
elin
g:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Som
e Te
chno
logy
has
legs
, so
me
do n
ot h
ave
legs
, and
so
me
have
gon
e be
lly u
p.
We’
ll st
art b
y em
aini
ng th
e fu
ndam
enta
l tec
hnol
ogie
s (I
/O
pack
agin
g et
c) th
en e
xplo
re o
me
of th
ese
tech
nolo
gies
in d
epth
a
bit l
ater
.
Wh
at D
oes
Th
is A
ll M
ean
?
ED
O
BE
DO
FP
M
SL
DR
AM
DD
R II
DD
RS
DR
AM
SD
RA
M
D-R
DR
AM
ES
DR
AM
FC
RA
M
RL
DR
AM
xDD
R II
net
DR
AM
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Wha
t is
a “g
ood”
sys
tem
?
It’s
all a
bout
the
cost
of a
sy
stem
. Thi
s is
a m
ulti-
dim
ensi
onal
trad
eoff
prob
lem
. E
spec
ially
toug
h w
hen
the
rela
tive
cost
fact
ors
of p
ins,
die
ar
ea, a
nd th
e de
man
ds o
f ba
ndw
idth
and
late
ncy
keep
s on
ch
angi
ng. G
ood
deci
sion
s fo
r on
e ge
nera
tion
may
not
be
good
fo
r fu
ture
gen
erat
ions
. Thi
s is
w
hy w
e do
n’t k
eep
a D
RA
M
prot
ocol
for
a lo
ng ti
me.
FP
M
last
ed a
whi
le, b
ut w
e’ve
qui
ckly
pr
ogre
ssed
thro
ugh
ED
O,
SD
RA
M, D
DR
/RD
RA
M, a
nd
now
DD
R II
and
wha
teve
r els
e is
on
the
horiz
on.
Co
st -
Ben
efit
Cri
teri
on
Lo
gic
Ove
rhea
d
Po
wer
C
on
sum
pti
on
Pac
kag
e C
ost
Test
an
d
DR
AM
Sys
tem
Des
ign
Ban
dw
idth
Lat
ency
Imp
lem
enta
tio
n
Inte
rco
nn
ect
Co
st
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Now
we’
ll re
ally
get
our
han
ds
dirt
y, a
nd tr
y to
bec
ome
DR
AM
de
sign
ers.
Tha
t is,
we
wan
t to
unde
rsta
nd th
e tr
adeo
ffs, a
nd
desi
gn o
ur o
wn
mem
ory
syst
em
with
DR
AM
cel
ls. B
y do
ing
this
, w
e ca
n ga
in s
ome
insi
ght i
nto
som
e of
the
basi
s of
cla
ims
by
prop
onen
ts o
f var
ious
DR
AM
m
emor
y sy
stem
s.
A M
emor
y S
yste
m is
a s
yste
m
that
has
man
y pa
rts.
It’s
a s
et o
f te
chno
logi
es a
nd d
esig
n de
cisi
ons.
All
of th
e pa
rts
are
inte
r-re
late
d, b
ut fo
r th
e sa
ke o
f di
scus
sion
, we’
ll sp
lite
the
com
pone
nts
into
ova
ls s
een
here
, and
try
to e
xam
ine
each
pa
rt o
f a D
RA
M s
yste
m
sepa
rate
ly.
Mem
ory
Sys
tem
Des
ign
DR
AM
Mem
ory
S
yste
m
Top
olo
gy
I/O T
ech
no
log
y
Acc
ess
Pro
toco
l
DR
AM
Ch
ipA
rch
itec
tureClo
ck N
etw
ork
Ro
w B
uff
er
Ad
dre
ss M
app
ing
Man
agem
ent
Pin
Co
un
t
Ch
ip P
acka
gin
g
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Pro
fess
or J
acob
has
sho
wn
yoou
som
e ni
ce ti
min
g di
agra
ms,
I to
o w
ill s
how
you
so
me
nice
tim
ing
diag
ram
s, b
ut
the
timin
g di
agra
ms
are
a si
mpl
ifica
tion
that
hid
es th
e de
tails
of i
mpl
emet
atio
n. W
hy
don’
t the
y ju
st r
un th
e sy
stem
at
XX
X M
Hz
like
the
othe
r gu
y?
The
n th
e la
tenc
y w
ould
be
muc
h be
tter,
and
the
band
wid
th w
ould
be
ext
rem
e. P
erha
ps th
ey c
an’t,
an
d w
e’ll
expl
ain
why
. To
unde
rsta
nd th
e re
ason
why
so
me
syst
ems
can
oper
ate
at
XX
X M
Hz
whi
le o
ther
s ca
nnot
, w
e m
ust g
o di
ggin
g pa
st th
e ni
ce
timin
g di
gram
s an
d th
e ar
chite
ctur
al b
lock
dia
gram
s an
d se
e w
hat t
urns
up
unde
rnea
th.
So
unde
rnea
th th
e tim
ing
diag
ram
, we
find
this
....
DR
AM
Inte
rfac
es
Th
e D
igit
al F
anta
sy
Ro
w
r 0
d0
d0
d0
d0
Co
l
Dat
a
a 0r 1
d1
d1
d1
d1
RA
Sla
ten
cyC
AS
late
ncy
Pip
elin
ed A
cces
s
Pre
ten
d t
hat
th
e w
orl
d lo
oks
like
th
is
Bu
t...
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
We
don’
t get
nic
e sq
uare
or
even
nic
ely
shap
ed w
avef
orm
s.
Jitte
r, sk
ew, e
tc. V
ddq
and
Vss
q ar
e th
e vo
ltage
sup
plie
s to
the
I/O
pad
s on
the
DR
AM
chi
ps. T
he
sign
al b
ounc
es a
roun
d, a
nd v
ery
non
idea
l. S
o w
hat a
re th
e pr
oble
ms,
and
wha
t are
the
solu
tion(
s) th
at a
re u
sed
to s
olve
th
ese
prob
lem
s? (
note
, the
158
ps
ske
w o
n pa
ralle
l dat
a ch
anne
ls If
you
r cy
cle
time
is
10ns
, or
10,0
00ps
, a s
kew
of
158
ps is
no
big
deal
, but
if y
our
cycl
e tim
e is
1ns
, or
1000
ps,
then
a s
kew
of 1
58ps
is a
big
de
al)
Alre
ady,
we
see
hint
s of
som
e pr
oble
ms
as w
e tr
y to
pus
h sy
stem
s to
hig
her
and
high
er
cloc
k fr
eque
ncie
s.
Th
e R
eal W
orl
dV
DD
Q(P
ad
)FCR
AM
sid
e
Con
trol
ler
side
VS
SQ
(Pa
d)
DQ
S (
Pin
)
DQ
0-1
5 (
Pin
)
DQ
S (
Pin
)D
Q0
-15 (
Pin
)
ske
w=
15
8p
se
cske
w=
10
2p
se
c
*To
shib
a P
rese
nta
tio
n, D
enal
i Mem
Co
n 2
002
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Firs
t, w
e ha
ve to
intr
oduc
e th
e co
ncep
t tha
t sig
nal p
ropa
gatio
n ta
kes
finite
tim
e. L
imite
d by
the
spee
d of
ligh
t, or
rat
her
idea
l tr
ansm
issi
on li
nes
we
shou
ld
have
spe
ed o
f app
roxi
mat
ely
2/3
the
spee
d of
ligh
t. T
hat g
ets
us
20cm
/ns.
All
sign
als,
incl
udin
g sy
stem
wid
e cl
ock
sign
als
has
to
be s
ent o
n a
syst
em b
oard
, so
if yo
u se
nt a
clo
ck s
igna
l fro
m
poin
t A to
poi
nt B
on
an id
eal
sign
al li
ne, p
oint
B w
on’t
be a
ble
to te
ll th
at th
e cl
ock
has
chan
ge
until
at t
he e
arlie
st, 1
/20
ns/c
m *
di
stan
ce la
ter
that
the
cloc
k ha
s ris
en.
The
n ag
ain,
PC
boa
rds
are
not
exac
tly id
eal t
rans
mis
sion
line
s.
(rin
ging
effe
ct, d
rive
stre
ngth
, et
c)T
he c
once
pt o
f “S
ynch
rono
us”
brea
ks d
own
whe
n di
ffere
nt
part
s of
the
syst
em o
bser
ve
diffe
rent
clo
cks.
Kin
d of
like
re
lativ
ity
Sig
nal
Pro
pag
atio
n
Idea
l Tra
nsm
issi
on
Lin
e
AB
PC
Bo
ard
+ M
od
ule
Co
nn
ecto
rs +
V
aryi
ng
Ele
ctri
cal L
oad
s
= R
ath
er n
on
-Id
eal T
ran
smis
sio
n L
ine
~ 0.
66c
= 20
cm
/ns
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Whe
n w
e bu
ild a
“sy
nchr
onou
s sy
stem
” on
a P
CB
boa
rd, h
ow
do w
e di
strib
ute
the
cloc
k si
gnal
? D
o w
e w
ant a
slid
ing
time
dom
ain?
Is H
Tre
e do
-abl
e to
N-m
odul
es in
par
alle
l? S
kew
co
mpe
nsat
ion?
Clo
ckin
g Is
sues
0thN
th
0thN
th
Clk
SR
C
Clk
SR
C Wh
at K
ind
of
Clo
ckin
g S
yste
m?
Fig
ure
1:
Slid
ing
Tim
e
Fig
ure
2:
H T
ree?
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
We
wou
ld w
ant t
he c
hips
to b
e on
a “
glob
al c
lock
”, e
very
one
is
perf
ectly
syn
chro
nous
, but
sin
ce
cloc
k si
gnal
s ar
e de
liver
ed
thro
ugh
wire
s, d
iffer
ent c
hips
in
the
syst
em w
ill s
ee th
e ris
ing
edge
of a
clo
ck a
littl
e bi
t ear
lier/
late
r th
an o
ther
chi
ps.
Whi
le a
n H
-Tre
e m
ay w
ork
for
a lo
w fr
eq s
yste
m, w
e re
ally
nee
d a
cloc
k fo
r se
ndin
g (w
ritin
g)
sign
als
from
the
cont
rolle
r to
the
chip
s, a
nd a
noth
er o
ne fo
r sn
ding
sig
nals
from
chi
ps to
co
ntro
ller
(rea
ding
)
Clo
ckin
g Is
sues
0thN
th
0thN
th
Clk
SR
C
Clk
SR
C
We
nee
d d
iffe
ren
t “cl
ock
s” fo
r R
/W
Fig
ure
1:
Wri
te D
ata
Fig
ure
2:
Rea
d D
ata
Sig
nal
Dir
ecti
on S
ign
al D
irec
tio
n
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
We
purp
osef
ully
“rou
ted
path
#2
to b
e a
bit l
onge
r th
an p
ath
#1 to
ill
ustr
ate
the
poin
t in
betw
een
the
sign
al p
ath
leng
th
diffe
rent
ials
. As
illus
trat
ed,
sign
als
will
rea
ch lo
ad B
at a
la
ter
time
than
load
A s
impl
y be
caus
e it
is fa
rthe
r aw
ay fr
om
cont
rolle
r th
an lo
ad A
.
It is
als
o di
fficu
lt to
do
path
le
ngth
and
impe
denc
e m
atch
ing
on a
sys
tem
boa
rd. S
omet
imes
he
roic
effo
rts
mus
t be
utili
zed
to
get u
s a
nice
“pa
ralle
l” bu
s.
Pat
h L
eng
th D
iffe
ren
tial
AC
ontr
olle
r
Path
#3
Path
#2
Path
#1
Bus
Sig
nal 2
Bus
Sig
nal 1
Inte
rmod
ule
Con
nect
ors
B
Hig
h F
req
uen
cy A
ND
Wid
e P
aral
lel
Bu
sses
are
Dif
ficu
lt t
o Im
ple
men
t
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
It’s
hard
to b
ring
the
Wid
e pa
ralle
l bus
from
poi
nt A
to p
oint
B
, but
it’s
eas
ier
to b
ring
in
smal
ler
grou
ps o
f sig
nals
from
A
to B
. To
ensu
re p
rope
r tim
ing,
w
e al
so s
end
alon
g a
sour
ce
sync
hron
ous
cloc
k si
gnal
that
is
path
leng
th m
atch
ed w
ith th
e si
gnal
gro
un it
cov
ers.
In th
is
figur
e, s
igna
l gro
ups
1,2,
and
3
may
hav
e so
me
timin
g sk
ew w
ith
resp
ect t
o ea
ch o
ther
, but
with
in
the
grou
p th
e si
gnal
s w
ill h
ave
min
imal
ske
w. (
smal
ler
chan
nel
can
be c
lock
ed h
ighe
r)
Su
bd
ivid
ing
Wid
e B
uss
es
Ob
stru
ctio
n
1
1 23
2
3
Nar
row
Ch
ann
els,
So
urc
e S
ynch
ron
ou
sL
oca
l Clo
ck S
ign
als
A
B
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ana
logy
, it’s
a lo
t har
der
to
sche
dule
8 p
eopl
e fo
r a m
eetin
g,
but a
lot e
asie
r to
sch
edul
e 2
mee
tings
with
4 p
eopl
e ea
ch.
The
res
ults
of t
he tw
o m
eetin
g ca
n be
cor
rela
ted
late
r.
Why
Su
bd
ivis
ion
Hel
ps
Su
bC
han
nel
1
Su
bC
han
nel
2
Wo
rst
Cas
esk
ew o
f {C
han
1 +
Ch
an 2
}
Wo
rst
Cas
esk
ew o
f C
han
1
Wo
rst
Cas
esk
ew o
f C
han
2
Wo
rst
Cas
e S
kew
mu
st b
e C
on
sid
ered
in S
yste
m T
imin
g
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
A “
Sys
tem
” is
a ha
rd th
ing
to
desi
gn. E
spec
ially
one
that
al
low
s en
d us
ers
to p
erfo
rm
confi
gura
tions
that
will
impa
ct
timin
g. T
o gu
aren
tee
func
tiona
l co
rrec
tnes
s of
the
syst
em, a
ll co
rner
cas
es o
f var
ianc
es in
lo
adin
g an
d tim
ing
mus
t be
acco
unte
d fo
r.
Tim
ing
Var
iati
on
s
Co
ntr
olle
r
Co
ntr
olle
r
4 L
oad
s
1 L
oad
Clo
ck
Cm
d t
o 1
Lo
ad
Cm
d t
o 4
Lo
ads
Ho
w m
any
DIM
Ms
in S
yste
m?
Ho
w m
any
dev
ices
on
eac
h D
IMM
?
Infi
nit
e va
riat
ion
s o
n t
imin
g!
Wh
o b
uilt
th
e m
emo
ry m
od
ule
?
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
To e
nsur
e th
at a
ligh
tly lo
aded
sy
stem
and
a fu
lly lo
aded
sy
stem
do
not d
iffer
sig
nific
antly
in
tim
ing,
we
eith
er h
ave
dupl
icat
e si
gnal
s se
nt to
di
ffere
nt m
emor
y m
odul
es, o
r w
e ha
ve th
e sa
me
sign
al li
ne,
but t
he s
igna
l lin
e us
es v
aria
ble
stre
ngth
s to
driv
e th
e I/O
pad
s,
depe
ndin
g on
if th
e sy
stem
has
1,
2,3
or 4
load
s.
Lo
adin
g B
alan
ce
Co
ntr
olle
r
Co
ntr
olle
r
Co
ntr
olle
r
Co
ntr
olle
rD
up
licat
eS
ign
alL
ines
Var
iab
leS
ign
alD
rive
S
tren
gth
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Sel
f Exp
lana
tory
. top
olog
y de
term
ines
load
ing
and
sign
al
prop
agat
ion
leng
ths.
Top
olo
gy
Co
ntr
olle
r
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip
DR
AM
Ch
ip?
DR
AM
Sys
tem
To
po
log
y D
eter
min
es
and
Sig
nal
Pro
pag
atio
n L
eng
ths
Ele
ctri
cal L
oad
ing
Co
nd
itio
ns
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ver
y si
mpl
e to
polo
gy. T
he c
lock
si
gnal
that
turn
s ar
ound
is v
ery
nice
. Sol
ves
prob
lem
of n
eedi
ng
mul
tiple
clo
cks.
SD
RA
M T
op
olo
gy
Exa
mp
le
Com
man
d &
Dat
a bu
s
Sin
gle
Ch
ann
elS
DR
AM
Co
ntr
olle
r
Add
ress
(64
bits
)(1
6 bi
ts)
Loa
din
g Im
bal
ance
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
x16
DR
AM
Chi
p
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
All
sign
als
in th
is to
polo
gy, A
ddr/
Cm
d/D
ata/
Clo
ck a
re s
ent f
rom
po
int t
o po
int o
n ch
anne
ls th
at is
pa
th le
ngth
mat
ched
by
defin
ition
.
RD
RA
M T
op
olo
gy
Exa
mp
le
RD
RA
MC
on
tro
ller
Con
trol
ler
Chi
pP
acke
ts t
rave
ling
do
wn
Par
alle
l Pat
hs.
Ske
w is
m
inim
al b
y d
esig
n.
clo
cktu
rns
aro
un
d
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
RS
L vs
SS
TL2
etc
.
(like
EC
L vs
TT
L of
ano
ther
era
)
Wha
t is
“Log
ic L
ow”,
wha
t is
“Log
ic H
igh”
? D
iffer
ent E
lect
rical
S
igna
lling
pro
toco
ls d
iffer
on
volta
ge s
win
g, h
igh/
low
leve
l, et
c.
delta
t is
on
the
orde
r of
ns,
we
wan
t it t
o be
on
the
orde
r of
ps.
I/O T
ech
no
log
y ∆∆∆∆ t
∆∆∆∆ v
Lo
gic
Hig
h
Lo
gic
Lo
wT
ime
Sle
w R
ate
= ∆∆∆∆
v∆∆∆∆
t
Sm
alle
r ∆∆∆∆
v =
Sm
alle
r ∆∆∆∆
t at
sam
e sl
ew r
ate
Incr
ease
Rat
e o
f b
its/
s/p
in
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Use
d on
clo
ckin
g sy
stem
s, i.
e.
RD
RA
M (
all c
lock
sig
nals
are
pa
irs, c
lk a
nd c
lk#)
.
Hig
hest
noi
se to
lera
nce,
doe
s no
t nee
d as
man
y gr
ound
si
gnal
s. W
here
as
sing
led
ende
d si
gnal
s ne
ed m
any
grou
nd
conn
ectio
ns. A
lso
diffe
rent
ial
pair
sign
als
may
be
cloc
ked
even
hig
her,
so p
in-b
andw
idth
di
sadv
anta
ge is
not
nea
rly 2
:1
as im
plie
d by
the
diag
ram
.
I/O -
Dif
fere
nti
al P
air
Diff
eren
tial P
air
Tran
smis
sion
Lin
e
Sin
gle
End
ed T
rans
mis
sion
Lin
e
Incr
ease
Rat
e of
bit
s/s/
pin
?
Cos
t P
er P
in?
Pin
Cou
nt?
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
One
of s
ever
al w
ays
on th
e ta
ble
to fu
rthe
r in
crea
se th
e bi
t-ra
te o
f th
e in
terc
onne
cts.
I/O -
Mu
lti L
evel
Lo
gic
tim
e
logi
c 01
ra
nge
logi
c 00
ra
nge
voltage
logi
c 10
ra
nge
logi
c 11
ra
nge
Incr
ease
Rat
e of
bit
s/s/
pin
Vre
f_2
Vre
f_0
Vre
f_1
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Diff
eren
t pac
kagi
ng ty
pes
impa
ct
cost
s an
d sp
eed.
Slo
w p
arts
can
us
e th
e ch
eape
st p
acka
ging
av
aila
ble.
Fas
ter
part
s m
ay h
ave
to u
se m
ore
expe
nsiv
e pa
ckag
ing.
Thi
s ha
s lo
ng b
e ac
cept
ed in
the
high
er m
argi
n pr
oces
sor
wor
ld, b
ut to
DR
AM
, ea
ch c
ent h
as to
har
d fo
ught
for.
To s
ome
exte
nt, t
he d
eman
d fo
r hi
gher
per
form
ance
is p
ushi
ng
mem
ory
mak
ers
to u
se m
ore
expe
nsiv
e pa
ckag
ing
to
acco
mm
odat
e hi
gher
freq
uenc
y pa
rts.
Whe
n R
AM
BU
S fi
rst
spec
’ed
FB
GA
, mod
ule
mak
ers
com
plai
ned,
sin
ce th
ey h
ave
to
purc
hase
exp
ensi
ve e
quip
men
t to
val
idat
e th
at c
hips
wer
e pr
oper
ly s
olde
red
to th
e m
odul
e bo
ard,
whe
reas
som
ethi
ng li
ke
TS
OP
can
be
done
with
vis
ual
insp
ectio
n.
Pac
kag
ing
DIP
“go
od
old
day
s”
FB
GA
LQ
FP
TS
OP
SO
JS
mal
l Ou
tlin
e J-
lead
Th
in S
mal
l Ou
tlin
e
Lo
w P
rofi
le Q
uad
Fin
e B
all G
rid
Arr
ay
Fla
t P
acka
ge
Pac
kag
e
Fea
ture
sTa
rget
Sp
ecifi
cati
on
Pac
kage
FB
GA
LQF
P
Spe
ed80
0MB
p55
0Mbp
s
Vdd
/Vdd
q2.
5V/2
.5V
(1.
8V)
Inte
rfac
eS
ST
L_2
Row
Cyc
le
Tim
e t R
C
35ns
Mem
ory
Ro
adm
ap fo
rH
ynix
Net
DD
R II
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
16 b
it w
ide
com
man
d I h
ave
to
send
from
A to
B, I
nee
d 16
pin
s,
or if
I ha
ve le
ss th
an 1
6, I
need
m
ultip
le c
ycle
s.
How
man
y bi
ts d
o I n
eed
to s
end
from
poi
nt A
to p
oint
B?
How
m
any
pins
do
I get
?
Cyc
les
= B
its/P
ins.
Acc
ess
Pro
toco
l
Sin
gle
C
ycle
C
md
Mu
ltip
le
Cyc
le
Cm
d
Cm
d
Dat
a
Cm
d
Dat
a
r 0
d0
d0
d0
d0
r 0r 0
r 0r 0
d0
d0
d0
d0
Sin
gle
Cyc
le C
om
man
d
Mu
ltip
le C
ycle
Co
mm
and
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
The
re is
inhe
rant
late
ncy
betw
een
issu
ance
of a
rea
d co
mm
and,
and
the
resp
onse
of
the
chip
with
dat
a. T
o in
crea
se
effic
ienc
y, a
pip
elin
e st
ruct
ure
is
nece
ssar
y to
obt
ain
full
utili
zatio
n of
the
com
man
d,
addr
ess
and
data
bus
ses.
D
iffer
ent f
rom
an
“ord
inar
y”
pipe
line
on a
pro
cess
or, a
m
emor
y pi
pelin
e ha
s da
ta
flow
ing
in b
oth
dire
ctio
ns.
Arc
hite
ctur
e w
ise,
we
shou
ld b
e co
ncer
ned
with
full
utili
zatio
n ev
eryw
here
, so
we
can
use
the
leas
t num
ber
of p
ins
for
the
grea
test
ben
efit,
but i
n ac
tual
us
e, w
e ar
e us
ually
con
cern
ed
with
full
utili
zatio
n of
the
data
bu
s.
Acc
ess
Pro
toco
l (r/
r)
Co
ntr
ol
DR
AM
DR
AM
DR
AM
DR
AM
Ro
w
r 0
d0
d0
d0
d0
Co
l
Dat
a
a 0r 1
d1
d1
d1
d1
RA
Sla
ten
cyC
AS
late
ncy
Pip
elin
ed A
cces
s
Co
nse
cuti
ve C
ach
e L
ine
Rea
d R
equ
ests
to
Sam
e D
RA
M R
ow
a =
Act
ive
(op
en p
age)
r =
Rea
d (
Co
lum
n R
ead
)
d =
Dat
a (D
ata
chu
nk)
Co
mm
and
Dat
a
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
The
DR
AM
chi
ps d
eter
min
e th
e la
tenc
y of
dat
a af
ter
a re
ad
com
man
d is
rec
eive
d, b
ut th
e co
ntro
ller
dete
rmin
es th
e tim
ing
rela
tions
hip
betw
een
the
writ
e co
mm
and
and
the
data
bei
ng
writ
ten
to th
e dr
am c
hips
.
(If t
he D
RA
M d
evic
e ca
nnot
ha
ndle
pip
elin
ed R
/W, t
hen.
..)
Cas
e 1:
Con
trol
ler
send
s w
rite
data
at s
ame
time
as th
e w
rite
com
man
d to
diff
eren
t dev
ices
(p
ipel
ined
)
Cas
e 2:
Con
trol
ler
send
s w
rite
data
at s
ame
time
as th
e w
rite
com
man
d to
sam
e de
vice
. (no
t pi
pelin
ed)
Acc
ess
Pro
toco
l (r/
w)
w0
d0
d0
d0
d0
Co
l
Dat
a
r 1
d1
d1
d1
d1
Cas
e 2:
Rea
d F
ollo
win
g a
Wri
te C
om
man
d t
o S
ame
DR
AM
Dev
ice
w0
d0
d0
d0
d0
Co
l
Dat
a
r 1
d1
d1
d1
d1
Cas
e 1:
Rea
d F
ollo
win
g a
Wri
te C
om
man
d t
o D
iffe
ren
t D
RA
M D
evic
es
Sen
se A
mp
s
Co
lum
n D
eco
der
Dat
a In
/Ou
tB
uff
ers
DR
AM
On
e D
atap
ath
- T
wo
Co
mm
and
s
w0
d0
d0
d0
d0
Co
l
Dat
a
r 1
d1
d1
d1
d1
So
ln: D
elay
Dat
a o
f Wri
te C
om
man
d t
o m
atch
Rea
d L
aten
cy
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
To in
crea
se “
effic
ienc
y”,
pipe
lines
is r
equi
red.
How
man
y co
mm
ands
mus
t one
dev
ice
supp
ort c
oncu
rren
tly?
2? 3
? 4?
(de
pend
s on
wha
t?)
Imag
ine
we
mus
t inc
reas
t dat
a ra
te (
high
er p
in fr
eq),
but
allo
w
DR
AM
cor
e to
ope
rate
slig
htly
sl
ower
. (2X
pin
freq
., sa
me
core
la
tenc
y)
Thi
s is
sue
ties
acce
ss p
roto
col
to in
tern
al D
RA
M a
rchi
tect
ure
issu
es.
Acc
ess
Pro
toco
l (p
ipel
ines
)
r 1
d1
d1
d1
d1
Co
l
Dat
a
r 2
d2
d2
d2
d2
Co
l
Dat
a
CA
Sla
ten
cy
r 0
d0
d0
d0
d0
CA
Sla
ten
cy
r 0r 1
r 2
d0d
0d
0d
0d
1d
1d
1d
1d2d
2d
2d
2
Th
ree
Bac
k-to
-Bac
k P
ipel
ined
Rea
d C
om
man
ds
“Sam
e” L
aten
cy, 2
X p
in f
req
uen
cy, D
eep
er P
ipel
ine
Wh
en p
in f
req
uen
cy in
crea
ses,
ch
ips
mu
st e
ith
er
red
uce
“re
al la
ten
cy”,
or
sup
po
rt lo
ng
er b
urs
ts, o
r p
ipel
ine
mo
re c
om
man
ds.
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
440B
X u
sed
132
pins
to c
ontr
ol
a si
ngle
SD
RA
M c
hann
el, n
ot
coun
ting
Pw
r &
GN
D. n
ow 8
45
chip
set o
nly
uses
102
.
Als
o sl
ower
ver
sion
s. 6
6/10
0
Als
o pa
ge b
urst
, an
entir
e pa
ge.
Bur
st le
ngth
pro
gram
med
to
mat
ch c
ache
line
size
. (i.e
. 32
byte
= 2
56 b
its =
4 c
ycle
s of
64
bits
)
Late
ncy
as s
een
by th
e co
ntro
ller
is r
eally
CA
S +
1
cycl
es .
Ou
tlin
e
•B
asic
s
•D
RA
M E
volu
tio
n: S
tru
ctu
ral P
ath
•A
dva
nce
d B
asic
s
•D
RA
M E
volu
tio
n: I
nte
rfac
e P
ath
•S
DR
AM
, DD
R S
DR
AM
, RD
RA
M M
emo
ry S
yste
m
Co
mp
aris
on
s•
Pro
cess
or-
Mem
ory
Sys
tem
Tre
nd
s•
RL
DR
AM
, FC
RA
M, D
DR
II M
emo
ry S
yste
ms
Su
mm
ary
•F
utu
re In
terf
ace
Tren
ds
& R
esea
rch
Are
as
•P
erfo
rman
ce M
od
elin
g:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
SD
RA
M S
yste
m In
Det
ail
Sin
gle
Ch
ann
elS
DR
AM
Co
ntr
olle
r
Dim
m1
Dim
m2
Dim
m3
Dim
m4
Dat
a B
us
Ad
dr
& C
md
Ch
ip (
DIM
M)
Sel
ect
“Mes
h T
op
olo
gy”
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
SD
RA
M: i
nexp
ensi
ve
pack
agin
g, lo
wes
t cos
t (LV
TT
L si
gnal
ing)
, sta
ndar
d 3.
3V s
uppl
y vo
ltage
. DR
AM
cor
e an
d I/O
sh
are
sam
e po
wer
sup
ply.
“Pow
er c
ost”
is b
etw
een
560m
W
and
1W p
er c
hip
for
the
dura
tion
of th
e ca
che
line
burs
t. (N
ote:
it
cost
s po
wer
just
to k
eep
lines
st
ored
in s
ense
am
p/ro
w b
uffe
rs,
som
ethi
ng fo
r ro
w b
uffe
r m
anag
emen
t pol
icie
s to
thin
k ab
out.)
Abo
ut 2
/7 o
f pin
s us
ed fo
r A
ddr,
2/7
used
for
Dat
a, 2
/7 u
sed
fo
Pw
r/G
nd, a
nd 1
/7 u
sed
for
cmd
sign
als.
Row
Com
man
ds a
nd c
olum
n co
mm
ands
are
sen
t on
the
sam
e bu
s, s
o th
ey h
ave
to b
e de
mul
tiple
xed
insi
de th
e D
RA
M
and
deco
ded.
SD
RA
M C
hip
133
MH
z (7
.5n
s cy
cle
tim
e)25
6 M
Bit
54 p
in
14 P
wr/
Gn
d16
Dat
a15
Ad
dr
7 C
md
1 C
lk1
NC
Mu
ltip
lexe
d C
om
man
d/A
dd
ress
Bu
s
Pro
gra
mm
able
Bu
rst
Len
gth
, 1,2
,4 o
r 8
Su
pp
ly V
olt
age
of
3.3V
LVT
TL
Sig
nal
ing
(0.
8V t
o 2
.0V
)
Qu
ad B
anks
Inte
rnal
ly
Lo
w L
aten
cy, C
AS
= 2
, 3
Co
nd
itio
n S
pec
ifica
tio
nC
ur.
Pw
r
Ope
ratin
g (A
ctiv
e) B
urst
= C
ontin
ous
300m
A1W
Ope
ratin
g (A
ctiv
e) B
urst
= 2
170m
A56
0mW
Sta
ndby
(A
ctiv
e) A
ll ba
nks
activ
e60
mA
200m
W
Sta
ndby
(po
wer
dow
n) A
ll ba
nks
inac
tive
2mA
6.6m
W
TS
OP
(0 t
o 3
.3V
rai
l to
rai
l.)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
We’
ve s
pent
som
e tim
e di
scus
sing
som
e pi
pelin
ed b
ack
to b
ack
read
com
man
ds s
ent t
o th
e sa
me
chip
, now
let’s
try
to
pipe
line
com
man
ds to
diff
eren
t ch
ips.
In o
rder
for
the
mem
ory
cont
rolle
r to
be
able
to la
tch
in
data
on
the
data
bus
on
cons
ecut
ive
cycl
es, c
hip
#0 h
as
to h
old
the
data
val
ue p
ast t
he
risin
g ed
ge o
f the
clo
ck to
sat
isfy
th
e ho
ld ti
me
requ
irem
ents
, the
n ch
ip #
0 ha
s to
sto
p, a
llow
the
bus
to g
o “q
uiet
”, th
en c
hip
#1
can
star
t to
driv
e th
e da
ta b
us a
t le
ast s
ome
“set
up ti
me”
ahe
ad o
f th
e ris
ing
edge
of t
he n
ext c
lock
. C
lock
cyc
les
has
to b
e lo
ng
enou
gh to
tole
rate
all
of th
e tim
ing
requ
irem
ents
.
SD
RA
M A
cces
s P
roto
col (
r/r)
01
23
45
67
98
10
Bac
k-to
-bac
k M
emor
y R
ead
Acc
esse
s to
Diff
eren
t Chi
ps in
SD
RA
M
1211
13
read
com
man
d an
d ad
dres
s as
sert
ion
data
bus
util
izat
ion
CA
SL 3
Mem
ory
Con
trolle
r
SDR
AM
chip
# 0
SDR
AM
chip
# 1
1
42
Dat
a bu
s
1
3
24
Dat
a re
turn
fro
mch
ip #
1
Dat
a re
turn
fro
mch
ip #
0
chip
# 0
h
old
tim
eb
us
idle
tim
ech
ip #
1se
tup
tim
e
Clo
ck s
ign
al
2
3
4
Clo
ck C
ycle
s ar
e st
ill lo
ng e
noug
h to
al
low
for
pipe
lined
bac
k-to
-bac
k R
eads
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
I sho
w d
iffer
ent p
aths
, but
th
eses
sig
nals
are
sha
ring
the
bi-d
irect
iona
l dat
a bu
s. F
or a
re
ad to
follo
w a
writ
e to
a
diffe
rent
chi
p, th
e w
orst
cas
e sk
ew is
whe
n w
e w
rite
to th
e (N
-1)
th c
hip,
then
exp
ect t
o pi
pelin
e a
read
com
man
d in
the
next
cy
cle
right
beh
ind
it. T
he w
orst
ca
se s
igna
l pat
h sk
ew is
the
sum
of t
he d
ista
nces
. Isn
’t fr
om
N to
N e
ven
wor
se?
No,
SD
RA
M
does
not
sup
port
pip
elin
ed r
ead
behi
nd a
writ
e on
the
sam
e ch
ip.
Als
o, it
’s n
ot a
s ba
d as
I pr
ojec
t he
re, s
ince
rea
d cy
cles
are
ce
nter
alig
ned,
and
writ
es a
re
edge
alig
ned,
so
in e
ssen
ce, w
e ge
t 1 1
/2 c
ycle
s to
pip
elin
e th
is
case
, ins
tead
of j
ust 1
cyc
le.
Stil
l, th
is p
robl
em li
mits
the
freq
sc
alab
ility
of S
DR
AM
, an
idle
cy
cles
may
be in
sert
ed to
mee
t tim
ing.
Look
s Ju
st li
ke S
DR
AM
!
SD
RA
M A
cces
s P
roto
col (
w/r
)
0thN
thF
igu
re 1
:C
on
secu
tive
Rea
ds
0thN
thF
igu
re 1
:R
ead
Aft
erW
rite
Wo
rst
case
= D
ist(
N)
- D
ist(
0)
Wri
teR
ead
(N-1
)th
Wo
rst
case
= D
ist(
N)
+ D
ist(
N-1
)
Bu
s Tu
rn A
rou
nd
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Tim
ing
bubb
les.
Mor
e de
ad
cycl
es
SD
RA
M A
cces
s P
roto
col (
w/r
)
Mem
ory
Con
trolle
r
SDR
AM
chip
# 0
SDR
AM
chip
# 1
4
2
Dat
a bu
s
1
3
w0
d0
d0
d0
d0
Co
l
Dat
a
r 1
d1
d1
d1
d1
Rea
d F
ollo
win
g a
Wri
te C
om
man
d t
o S
ame
SD
RA
M D
evic
e
1 2
3
4
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Sin
ce d
ata
bus
has
a m
uch
light
er lo
ad, i
f we
can
use
bette
r si
gnal
ing
tech
nolo
gy, p
erha
ps
we
can
run
just
the
data
bus
at a
hi
gher
freq
uenc
y.
At t
he h
ighe
r fr
eque
ncy,
the
skew
s w
e ta
lked
abo
ut w
ould
be
terr
ible
with
a 6
4 bi
t wid
e da
ta
bus.
So
we
use
a so
urce
sy
ncho
nous
str
obe
sign
als
(cal
led
DQ
S)
that
is r
oute
d pa
ralle
l to
each
8 b
it w
ide
sub
chan
nel.
DD
R is
new
er, s
o le
t’s u
se lo
wer
co
re v
olta
ge, s
aves
on
pow
er
too!
DD
R S
DR
AM
Sys
tem
Sin
gle
Ch
ann
el
Dim
m1
Dim
m2
Dim
m3
DD
R
SD
RA
MC
on
tro
ller
Dat
a B
us
Ad
dr
& C
md
Ch
ip (
DIM
M)
Sel
ect
DQ
S (
Dat
a S
tro
be)
Sam
e To
po
log
yas
SD
RA
M
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Slig
htly
larg
er p
acka
ge, s
ame
wid
th fo
r A
ddr
and
Dat
a, n
ew
pins
are
2 D
QS
, Vre
f, an
d no
w
diffe
rent
ial c
lock
s. L
ower
sup
ply
volta
ge.
Low
vol
tage
sw
ing,
now
with
re
fere
nce
to V
ref i
nste
ad o
f (0.
8 to
2.0
V)
No
pow
er d
iscu
ssio
n he
re
beca
use
data
she
et (
mic
ron)
is
inco
mpl
ete.
Rea
d D
ata
retu
rned
from
DR
AM
ch
ips
now
get
s re
ad in
with
re
spec
t to
the
timin
g of
the
DQ
S
sign
als,
sen
t by
the
dram
chi
ps
in p
aral
lel w
ith th
e da
ta it
self.
The
use
of D
QS
intr
oduc
es
“bub
bles
” in
betw
een
burs
ts fr
om
diffe
rent
chi
ps, a
nd r
educ
es
band
wid
th e
ffici
ency
.
DD
R S
DR
AM
Ch
ip13
3 M
Hz
(7.5
ns
cycl
e ti
me)
16 P
wr/
Gn
d*
16 D
ata
15 A
dd
r7
Cm
d2
Clk
*7
NC
*
Mu
ltip
lexe
d C
om
man
d/A
dd
ress
Bu
s
Pro
gra
mm
able
Bu
rst
Len
gth
s, 2
, 4 o
r 8*
Su
pp
ly V
olt
age
of
2.5V
*
SS
TL
-2 S
ign
alin
g (
Vre
f +/
- 0.
15V
)
Qu
ad B
anks
Inte
rnal
ly
Lo
w L
aten
cy, C
AS
= 2
, 2.
5, 3
*
256
MB
it66
pin
2 D
QS
*1
Vre
f *
01
23
45
CA
SL
= 2
Clk
Clk
#
Rea
d
Dat
a
DQ
S
Cm
d
DQ
S P
re-a
mb
leDQ
S P
ost
-am
ble
TS
OP
(0 t
o 2
.5V
rai
l to
rai
l)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Her
e w
e se
e th
at tw
o co
nsec
utiv
e co
lum
n re
ad
com
man
ds to
diff
eren
t chi
ps o
n th
e D
DR
mem
ory
chan
nel
cann
ot b
e pl
aced
bac
k to
bac
k on
the
Dat
a bu
s du
e to
the
DQ
S
sign
al h
and-
off i
ssue
. The
y m
ay
be p
ipel
ined
with
one
idle
cyc
le
in b
etw
een
burs
ts.
Thi
s si
tuat
ion
is tr
ue fo
r al
l co
nsec
utiv
e ac
cess
es to
di
ffere
nt c
hips
, r/r.
r/w
. w/r.
(e
xcep
t w/w
, whe
n th
e co
ntro
ller
keep
s co
ntro
l of t
he D
QS
sig
nal,
just
cha
nges
targ
et c
hips
)
Bec
ause
of t
his
over
head
, sho
rt
nurs
ts a
re in
effic
ient
on
DD
R,
long
er b
urst
s ar
e m
ore
effic
ient
. (3
2 by
te c
ache
line
= 4
bur
st, 6
4 by
te li
ne =
8 b
urst
)
DD
R S
DR
AM
Pro
toco
l (r/
r)
Bac
k-to
-bac
k M
emor
y R
ead
Acc
esse
s to
Diff
eren
t Chi
ps in
DD
R S
DR
AM
Mem
ory
Con
trol
ler
SD
RA
Mch
ip #
0S
DR
AM
chip
# 1
d 0
Dat
a bu
s
01
23
45
CA
SL
= 2
Clk
Clk
#
Dat
a
DQ
S
Cm
d
DQ
S p
re-a
mb
leD
QS
po
st-a
mb
le
r 0
67
8
d1
r 1
d1
d1
d1
d0
d0
d0
d0
d 1
r 0
r 1
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ver
y di
ffere
nt fr
om S
DR
AM
. E
very
thin
g is
sen
t aro
und
in 8
(h
alf c
ycle
) pa
cket
s. M
ost
syst
ems
now
run
s at
400
MH
z,
but s
ince
eve
ryth
ing
is D
DR
, it’s
ca
lled
“800
MH
z”. T
he o
nly
diffe
renc
e is
that
pac
kets
can
on
ly b
e in
itiat
ed a
t the
ris
ing
edge
of t
he c
lock
, oth
er th
an
that
, the
re’s
no
diff
betw
een
400
DD
R a
nd 8
00.
Ver
y cl
ean
topo
logy
, ver
y cl
ever
cl
ocki
ng s
chem
e. N
o cl
ock
hand
off i
ssue
, hig
h ef
ficie
ncy.
Writ
e de
lay
impr
oves
mat
chin
g w
ith r
ead
late
ncy.
(no
t per
fect
, as
sho
wn)
sin
ce d
ata
bus
is 1
6 bi
ts w
ide,
eac
h re
ad c
omm
and
gets
16*
8=12
8 bi
ts b
ack.
Eac
h ca
chel
ine
fetc
h =
mul
tiple
pa
cket
s.
Up
to 3
2 de
vice
s.
RD
RA
M S
yste
m
RD
RA
MC
on
tro
ller
Bus
Clo
ck
Col
umn
Cm
d
Dat
a B
us
t CA
C(C
AS
acce
ss d
elay
)
w0
t CW
D(W
rite
del
ay)
t CA
C -
t CW
D
Pac
ket
Pro
toco
l : E
very
thin
g in
8 (
hal
f) c
ycle
pac
kets
r 2w
1
d 0d 2
d 1
Two
Wri
te C
om
man
ds
Fo
llow
ed b
y a
Rea
d C
om
man
d
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
RD
RA
M p
acke
ts d
oes
not r
e-or
der
the
data
insi
de th
e pa
cket
. To
com
pute
RD
RA
M la
tenc
y, w
e m
ust a
dd in
the
com
man
d pa
cket
tran
smis
sion
tim
e as
wel
l as
dat
a pa
cket
tran
smis
sion
tim
e.
RD
RA
M r
elie
s on
the
mul
titud
es
of b
anks
to tr
y to
mak
e su
re th
at
a hi
gh p
erce
ntag
e of
req
uest
s w
ould
hit
open
pag
es, a
nd o
nly
incu
r th
e co
st o
f a C
AS
, ins
tead
of
a R
AS
+ C
AS
.
Dir
ect
RD
RA
M C
hip
400
MH
z (2
.5n
s cy
cle
tim
e)
49 P
wr/
Gn
d*
16 D
ata
8 A
dd
r/C
md
4 C
lk*
6 C
TL
*2
NC
Sep
arat
e R
ow
-Co
l Co
mm
and
Bu
sses
Bu
rst
Len
gth
= 8
*
Su
pp
ly V
olt
age
of
2.5V
*
RS
L S
ign
alin
g (
Vre
f +/
- 0.
2V)
4/16
/32
Ban
ks In
tern
ally
*
Lo
w L
aten
cy, C
AS
= 4
to
6 f
ull
cycl
es*
256
MB
it86
pin
1 V
ref
*
FB
GA
Act
ive
read
read
pre
char
ge
dat
ad
ata
All
pac
kets
are
8 (
hal
f) c
ycle
s in
len
gth
,th
e p
roto
col a
llow
s n
ear
100%
ban
dw
idth
Act
ive
read
read
dat
ad
ata
uti
lizat
ion
on
all
chan
nel
s. (
Ad
dr/
Cm
d/D
ata)
(800
mV
rai
l to
rai
l)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
RD
RA
M p
rovi
des
high
ba
ndw
idth
, but
wha
t are
the
cost
s?R
AM
BU
S p
ushe
d in
man
y di
ffere
nt a
reas
sim
ulta
neou
sly.
T
he d
raw
back
was
that
with
new
se
t of i
nfra
stru
ctur
e, th
e co
sts
for
first
gen
erat
ion
prod
ucts
wer
e ex
horb
ant.
RD
RA
M D
raw
bac
ks
Sig
nifi
can
t C
ost
Del
ta fo
r F
irst
Gen
erat
ion
RS
L: S
epar
ate
Po
wer
Pla
ne
Co
ntr
ol L
og
ic -
Ro
w b
uff
ers
30%
die
co
stfo
r lo
gic
@64
Mb
it n
od
e
Hig
h F
req
uen
cyI/O
Tes
t an
d
Pac
kag
e C
ost
Act
ive
Dec
od
e L
og
ic +
Op
enR
ow
Bu
ffer
.(H
igh
po
wer
fo
r “q
uie
t” s
tate
)
Sin
gle
Ch
ipP
rovi
des
All
Dat
a B
its
for
Eac
h P
acke
t(P
ow
er)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Low
pin
cou
nt, h
ighe
r la
tenc
y.In
gen
eral
term
s, th
e sy
stem
co
mpa
rison
sim
ply
poin
ts o
ut
the
vario
us p
arts
that
RD
RA
M
exce
lls in
, i.e
. hig
h ba
ndw
idth
an
d lo
w p
in c
ount
., bu
t the
y al
so
have
long
er la
tenc
y, s
ince
it
take
s 10
ns
just
to m
ove
the
com
man
d fr
om th
e co
ntro
ller
onto
the
DR
AM
chi
p, a
nd
anot
her
10ns
just
to g
et th
e da
ta
from
the
DR
AM
chi
ps b
ack
onto
th
e co
ntro
ller
inte
rfac
e
Sys
tem
Co
mp
aris
on
SD
RA
MD
DR
RD
RA
M
Fre
qu
ency
(M
Hz)
133
133*
240
0*2
Pin
Co
un
t (D
ata
Bu
s)64
6416
Pin
Co
un
t (C
on
tro
ller)
102
101
33
Th
eore
tica
l Ban
dw
idth
(M
B/s
)10
6421
2816
00
Th
eore
tica
l Effi
cien
cy
(dat
a b
its/
cycl
e/p
in)
0.63
0.63
0.48
Su
stai
ned
BW
(M
B/s
)*65
598
610
72
Su
stai
ned
Effi
cien
cy*
(dat
a b
its/
cycl
e/p
in)
0.39
0.29
0.32
RA
S +
CA
S (
t RA
C)
(ns)
45 ~
50
45 ~
50
57 ~
67
CA
S L
aten
cy (
ns)
**22
~ 3
022
~ 3
040
~ 5
0
133
MH
z P
6 C
hip
set
+ S
DR
AM
CA
S L
aten
cy ~
80
ns
*Str
eam
Ad
d**
Lo
ad t
o u
se la
ten
cy
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
RD
RA
M m
oves
com
plex
ity fr
om
inte
rfac
e in
to D
RA
M c
hips
. Is
this
a g
ood
trad
e of
f? W
hat
does
the
futu
re lo
ok li
ke?
Dif
fere
nce
s o
f P
hilo
sop
hy
Co
mp
lexi
ty M
oved
to
DR
AM
SD
RA
M -
Var
ian
ts
Co
ntr
olle
rD
RA
MC
hip
s
Co
mp
lex
Inte
rco
nn
ect
Inex
pen
sive
Inte
rfac
e
RD
RA
M -
Var
ian
ts
Co
ntr
olle
rD
RA
MC
hip
s
Sim
plif
ied
Inte
rco
nn
ect
exp
ensi
veIn
terf
ace
Sim
ple
Lo
gic
Co
mp
lex
Lo
gic
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
To b
egin
with
, we
look
in a
cr
ysta
l bal
l to
look
for t
rend
s th
at
will
cau
se c
hang
es o
r lim
it sc
alab
ility
in a
reas
that
we
are
inte
rest
ed in
. IT
RS
= In
tern
atio
nal T
echn
olog
y R
oadm
ap fo
r S
emic
ondu
ctor
s.
Tran
sist
or F
requ
ecie
s ar
e su
ppos
ed to
nea
rly d
oubl
e ev
ery
gene
ratio
n, a
nd tr
ansi
stor
bu
dget
(as
indi
cate
d by
Mill
ion
Logi
c Tr
ansi
stor
s pe
r cm
^2)
are
proj
ecte
d to
dou
ble.
Inte
rcon
nect
s be
twee
n ch
ips
are
a di
ffere
nt s
tory
. Mea
sure
d in
ce
nts/
pin,
pin
cos
t dec
reas
es
only
slo
wly
, and
pin
bud
get
grow
s sl
owly
eac
h ge
nera
tion.
Pun
chlin
e: In
the
futu
re, F
ree
Tran
sist
ors
and
Cos
tly
inte
rcon
nect
s.
Tech
no
log
y R
oad
map
(IT
RS
)
2004
2007
2010
2013
2016
Sem
i Gen
erat
ion
(n
m)
9065
4532
22
CP
U M
Hz
3990
6740
1200
019
000
2900
0
ML
og
icTr
ansi
sto
rs/
cm^2
77.2
154.
330
961
712
35
Hig
h P
erf
chip
pin
co
un
t22
6330
1240
0953
3571
00
Hig
h P
erfo
rman
ce c
hip
cost
(ce
nts
/pin
)1.
881.
611.
681.
441.
22
Mem
ory
pin
co
st
(cen
ts/p
in)
0.34
-1.
390.
27 -
0.
840.
22 -
0.
340.
19 -
0.
390.
19 -
0.
33
Mem
ory
pin
co
un
t48
-160
48-1
6062
-208
81-2
7010
5-35
1
Fre
e Tr
ansi
sto
rs &
Co
stly
Inte
rco
nn
ects
Tren
d:
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
So
we
have
som
e ch
oice
s to
m
ake.
Inte
grat
ion
of m
emor
y co
ntro
ller
will
mov
e th
e m
emor
y co
ntro
ller
on d
ie, f
requ
ency
will
be
muc
h hi
gher
. Com
man
d-da
ta
path
will
onl
y cr
oss
chip
bo
unda
ries
twic
e in
stea
d of
4
times
. But
inte
rfac
ing
with
m
emor
y ch
ips
dire
ctly
mea
ns
that
you
are
to b
e lim
ited
by th
e lo
wes
t com
mon
den
omin
ator
. To
get h
ighe
st b
andw
idth
(fo
r a
give
n nu
mbe
r of
pin
s) A
ND
lo
wes
t lat
ency
, we’
ll ne
ed
cust
om R
AM
, mig
ht a
s w
ell b
e S
RA
M, b
ut it
will
be
proh
ibat
ivel
y ex
pens
ive
Ch
oic
es fo
r F
utu
re
DRAM
CP
U
DRAM
DRAM
DRAM
DRAM
CP
U
CP
U
CP
U
DR
AM
DRAM
DRAM
DRAM
DR
AM
DR
AM
DR
AM
Mem
ory
C
on
tro
ller
Dir
ect
Co
nn
ect
Cu
sto
m D
RA
M:
Hig
hes
t B
and
wid
th +
Lo
w L
aten
cy
Dir
ect
Co
nn
ect
Co
mm
od
ity
DR
AM
Lo
w B
and
wid
th +
Lo
w L
aten
cy
Dir
ect
Co
nn
ect
sem
i-co
mm
. DR
AM
:H
igh
Ban
dw
idth
+L
ow
/Mo
der
ate
Lat
ency
Ind
irec
t C
on
nec
tio
n
Inex
pen
sive
DR
AM
Hig
hes
t B
and
wid
th H
igh
est
Lat
ency
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Two
RD
RA
M c
ontr
olle
r m
eans
2
inde
pend
ent c
hann
els.
Onl
y 1
pack
et h
as to
be
gene
rate
d fo
r ea
ch 6
4 by
te c
ache
line
tr
ansa
ctio
n re
ques
t.
(ext
ra c
hann
el s
tore
s ca
che
cohe
renc
e da
ta. i
.e. I
bel
ong
to
CP
U#2
, exc
lusi
vely
.)
Ver
y ag
gres
sive
use
of a
vaila
ble
page
s on
RD
RA
M m
emor
y.
EV
7 +
RD
RA
M (
Co
mp
aq/H
P)
•R
DR
AM
Mem
ory
(2
Co
ntr
olle
rs)
•D
irec
t C
on
nec
tio
n t
o p
roce
sso
r
•75
ns
Lo
ad t
o u
se la
ten
cy
•12
.8 G
B/s
Pea
k b
and
wid
th
•6
GB
/s r
ead
or
wri
te b
and
wid
th
•20
48 o
pen
pag
es (
2 *
32 *
32)
16 16 16 16
64M
C
Eac
h c
olu
mn
rea
dfe
tch
es 1
28 *
4 =
512
b(d
ata)
16 16 16 16
64M
C
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
EV
7 ca
chel
ine
is 6
4 by
tes,
so
each
4-c
hann
el g
ange
d R
DR
AM
ca
n fe
tch
64 b
ytes
with
1 s
ingl
e pa
cket
.E
ach
DD
R S
DR
AM
cha
nnel
can
fe
tch
64 b
ytes
by
itsel
f. S
o w
e ne
ed 6
con
trol
lers
if w
e ga
ng
two
DD
R S
DR
AM
s to
geth
er in
to
one
chan
nel,
we
have
to r
educ
e th
e bu
rst l
engt
h fr
om 8
to 4
. S
hort
er b
urst
s ar
e le
ss e
ffici
ent.
Sus
tain
able
ban
dwid
th d
rops
.
Wh
at if
EV
7 U
sed
DD
R?
•P
eak
Ban
dw
idth
12.
8 G
B/s
•6
Ch
ann
els
of
133*
2 M
Hz
DD
R S
DR
AM
==
•6
Co
ntr
olle
rs o
f 6
64 b
it w
ide
chan
nel
s, o
r
•3
Co
ntr
olle
rs o
f 3
128
bit
wid
e ch
ann
els
* pa
ge h
it C
AS
+ m
emor
y co
ntro
ller
late
ncy.
** in
clud
ing
all s
igna
ls, a
ddre
ss, c
omm
and,
dat
a, c
lock
, not
incl
udin
g E
CC
or
pari
ty**
* 3
cont
rolle
r de
sign
is le
ss b
andw
idth
eff
icie
nt.
Syst
emE
V7
+ R
DR
AM
EV
7 +
6 co
ntro
ller
DD
R S
DR
AM
EV
7 +
3 co
ntro
ller
DD
R S
DR
AM
Lat
ency
75 n
s~
50 n
s*~
50 n
s*
Pin
coun
t~2
65**
+ P
wr/
Gnd
~ 60
0**
+ Pw
r/G
nd~
600*
* +
Pwr/
Gnd
Con
trol
ler
Cou
nt2
6***
3***
Ope
n pa
ges
2048
144
72
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
DD
R S
DR
AM
was
an
adva
nced
men
t fro
m S
DR
AM
, w
ith lo
wer
ed V
dd, n
ew e
lect
rical
si
gnal
inte
rfac
e (S
ST
L), n
ew
prot
ocol
, but
fund
amen
tally
the
sam
e tR
C ~
= 6
0ns.
RD
RA
M h
as
tRC
of ~
70ns
. All
com
para
ble
in
Row
rec
over
y tim
e.S
o w
hat’s
nex
t? W
hat’s
on
the
Hor
izon
? D
DR
II/F
CR
AM
/R
LDR
AM
/RD
RA
M-n
extG
en/
Ken
tron
? W
hat a
re th
ey, a
nd
wha
t do
they
brin
g to
the
tabl
e?
Wh
at’s
Nex
t?
•D
DR
II
•F
CR
AM
•R
LD
RA
M
•R
DR
AM
(Ye
llow
sto
ne
etc)
•K
entr
on
QB
M
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
DD
R II
is a
follo
w o
n to
DD
R
DD
R II
com
man
d se
ts a
re a
su
pers
et o
f DD
R S
DR
AM
co
mm
ands
.Lo
wer
I/O
vol
tage
mea
ns lo
wer
po
wer
for
I/O a
nd p
ossi
bly
fast
er
sign
al s
witc
hing
due
to lo
wer
rail
to r
ail v
olta
ge.
DR
AM
cor
e no
w o
pera
tes
at 1
:4
of d
ata
bus
frqu
ency
. val
ida
com
man
d m
ay b
e la
tche
d on
an
y gi
ven
risin
g ed
ge o
f clo
ck,
but m
ay b
e de
laye
d a
cycl
e si
nce
com
man
d bu
s is
run
ning
at
1:2
freq
uenc
y to
the
core
now
.In
a m
emor
y sy
stem
it c
an ru
n at
40
0 M
Hz
per
pin,
whi
le it
can
be
cran
ked
up to
800
MH
z pe
r pi
n in
an
embe
dded
sys
tem
with
out
conn
ecto
rs.
DD
R II
elim
inat
es th
e tr
ansf
er-
until
-inte
rrup
ted
com
man
ds, a
s w
ell a
s lim
its th
e bu
rst l
engt
h to
4
only
. (si
mpl
e to
test
)
DD
R II
- D
DR
Nex
t G
enL
ow
er I/
OVo
ltag
e (1
.8V
)D
RA
M c
ore
op
erat
es a
t1:
4 fr
eq o
f d
ata
bus
freq
(SD
RA
M 1
:1, D
DR
1:2
)
Bac
kwar
d C
om
pat
.to
DD
R (C
om
mo
n
mo
du
les
po
ssib
le)
400
Mb
ps
- m
ult
idro
p80
0 M
bp
s-p
oin
t to
po
int
FP
BG
A p
acka
ge
No
mo
re P
age-
Tran
sfer
-Un
til-
Inte
rru
pte
dC
om
man
ds
(rem
oves
sp
eed
pat
h)
Bu
rst
Len
gth
==
4 O
nly
! 4 B
anks
inte
rnal
ly(s
ame
as S
DR
AM
an
d D
DR
)W
rite
Lat
ency
= C
AS
-1
(in
crea
sed
Bu
s U
tiliz
atio
n)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Inst
ead
of a
con
trol
ler t
hat k
eeps
tr
ack
of c
ycle
s, w
e ca
n no
w h
ave
a “d
umbe
r” c
ontr
olle
r. C
ontr
ol is
no
w s
impl
e, k
ind
of li
ke S
RA
M.
part
I of
add
ress
one
cyc
le, p
art
II th
e ne
xt c
ycle
.
DD
R II
- C
on
tin
ued
Po
sted
Co
mm
and
sR
ead
Act
ive
dat
a
(RA
S)
(CA
S)
t RC
D
Rea
dA
ctiv
e
dat
a
(RA
S)
(CA
S)
t RC
D
SD
RA
M &
DD
R S
DR
AM
rel
ies
on
mem
ory
co
ntr
olle
r to
kn
ow
t R
CD
an
d is
sue
CA
S a
fter
tR
CD
for
low
est
late
ncy
.
Inte
rnal
co
un
ter
del
ays
CA
S c
om
man
d, D
RA
M c
hip
issu
es “
real
”co
mm
and
aft
er t
RC
D fo
r lo
wes
t la
ten
cy.
SD
RA
M &
DD
R
DD
R II
: Po
sted
CA
S
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
FC
RA
M is
a tr
adem
ark
of
Fuj
itsu.
Tos
hiba
man
ufac
ture
s un
der
this
trad
emar
k, S
amsu
ng
sells
Net
wor
k D
RA
M. S
ame
thin
g.ex
tra
die
area
dev
oted
to c
ircui
ts
that
low
ers
Row
Cyc
le d
own
to
half
of D
DR
, and
Ran
dom
A
cces
s (R
AC
) la
tenc
y do
wn
to
22 to
26n
s.W
rites
are
del
ay-m
atch
ed w
ith
CA
SL,
bet
ter
bus
utili
zatio
n.
FC
RA
M
Fast
Cyc
le R
AM
(ak
a N
etw
ork
-DR
AM
)
Fea
ture
sD
DR
SD
RA
MF
CR
AM
/Net
wo
rk-D
RA
M
Vdd
, Vdd
q2.
5 +
/- 0
.2V
2.5
+/-
0.1
5
Ele
ctric
al In
terf
ace
SS
TL-
2S
ST
L-2
Clo
ck F
requ
ency
100~
167
MH
z15
4~20
0 M
Hz
t RA
C~
40ns
22~
26ns
t RC
~60
ns25
~30
ns
# B
anks
4
4
Bur
st L
engt
h2,
4,8
2,4
Writ
e La
tenc
y1
Clo
ckC
AS
L -1
FC
RA
M/N
etw
ork
-DR
AM
loo
ks li
ke D
DR
+
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
With
fast
er D
RA
M tu
rn a
roun
d tim
e on
the
tRC
, a r
ando
m
acce
ss th
at h
its th
e sa
me
page
ov
er a
nd o
ver a
gain
will
hav
e th
e hi
ghes
t bus
util
izat
ion.
(W
ith
rand
om R
/W a
cces
ses)
Als
o, w
hy P
eak
BW
!= s
usta
ined
B
W. D
evia
tions
from
pea
k ba
ndw
idth
cou
ld b
e du
e to
ar
chite
ctur
e re
late
d is
sues
suc
h as
tRC
(ca
nnot
cyc
le D
RA
M
arra
ys to
gra
b da
ta o
ut o
f sam
e D
RA
M a
rray
and
re-
use
sens
e am
ps)
FC
RA
M C
on
tin
ued
Fast
er t
RC
allo
ws
Sam
sun
g t
o c
laim
hig
her
bu
s ef
fici
ency
* S
amsu
ng
Ele
ctro
nic
s, D
enal
i Mem
Co
n 2
002
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ano
ther
Var
iant
, but
RLD
RA
M is
ta
rget
ted
tow
ard
embe
dded
sy
stem
s. T
here
are
no
conn
ecto
r sp
ecifi
catio
ns, s
o it
can
targ
et a
hig
her f
requ
ency
off
the
bat.
RL
DR
AM
DR
AM
Typ
eF
req
uen
cyB
us
Wid
th
(per
ch
ip)
Pea
k B
and
wid
th
(per
Ch
ip)
Ran
do
m
Acc
ess
Tim
e (t
RA
C)
Ro
w C
ycle
T
ime
(tR
C)
PC
133
SD
RA
M13
316
200
MB
/s45
ns
60 n
s
DD
R 2
66
133
* 2
1653
2 M
B/s
45 n
s60
ns
PC
800
RD
RA
M
400
* 2
161.
6 G
B/s
60 n
s70
ns
FC
RA
M20
0 *
216
0.8
GB
/s25
ns
25 n
s
RLD
RA
M30
0 *
232
2.4
GB
/s25
ns
25 n
s
Co
mp
arab
le t
o F
CR
AM
in la
ten
cyH
igh
er F
req
uen
cy (
No
Co
nn
ecto
rs)
no
n-M
ult
iple
xed
Ad
dre
ss (
SR
AM
like
)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Infin
eon
prop
oses
that
RLD
RA
M
coul
d be
inte
grat
ed o
nto
the
mot
herb
oard
as
an L
3 ca
che.
64
MB
of L
3. S
have
s 25
ns
off o
f tR
AC
from
goi
ng to
SD
RA
M o
r D
DR
SD
RA
M. N
ot to
be
used
as
mai
n m
emor
y du
e to
cap
acity
co
nstr
aint
s.
RL
DR
AM
Co
nti
nu
ed
256M
bR
LD
RA
M
Pro
cess
or
Hig
h-e
nd P
C a
nd S
erv
er
X32
2.4
GB
/s
Mem
ory
C
ontr
olle
r
Nort
hbridge
256M
bR
LD
RA
M
X32
2.4
GB
/s
???
RLD
RA
M is
a g
reat
repla
cem
ent
to S
RA
M in L
3
ca
ch
e a
pp
lica
tio
ns b
eca
use
of its h
igh
de
nsity,
low
pow
er
and low
cost
*Infi
neo
n P
rese
nta
tio
n, D
enal
i Mem
Co
n 2
002
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Unl
ike
othe
r D
RA
M’s
. Ye
llow
ston
e is
onl
y a
volta
ge
and
I/O s
peci
ficat
ion,
no
DR
AM
A
FAIK
. R
AM
BU
S h
as le
arne
d th
eir
less
on, t
hey
used
exp
ensi
ve
pack
agin
g, 8
laye
r m
othe
rboa
rds,
and
add
ed c
ost
ever
ywhe
re. N
ow th
e ne
w p
itch
is “
high
er p
erfo
rman
ce w
ith
sam
e in
fras
truc
ture
”.
RA
MB
US
Yel
low
sto
ne
•B
i-D
irec
tio
nal
Dif
fere
nti
al S
ign
als
•U
ltra
low
200
mV
p-p
sig
nal
sw
ing
s
•8
dat
a b
its
tran
sfer
red
per
clo
ck
•40
0 M
Hz
syst
em c
lock
•3.
2 G
Hz
effe
ctiv
e d
ata
freq
uen
cy
•C
hea
p 4
laye
r P
CB
•C
om
mo
dit
y p
acka
gin
g
Sys
tem
Clo
ck
Dat
a1.
2 V
1.0
V
Oct
al D
ata
Rat
e (O
DR
) S
ign
alin
g
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Qua
d B
and
Mem
ory
Use
s F
et s
witc
hes
to c
ontr
ol
whi
ch D
IMM
sen
ds o
utpu
t.Tw
o D
DR
mem
ory
chip
s ar
e in
terle
aved
to g
et Q
uad
mem
ory.
Adv
anta
ges,
use
s st
anda
rd
DD
R c
hips
, ext
ra c
ost i
s lo
w,
only
the
wra
pper
ele
ctro
nics
. M
odifi
catio
n to
mem
ory
cont
rolle
r re
quire
d, b
ut m
inim
al.
Has
to u
nder
stan
d th
at d
ata
is
bein
g bu
rst b
ack
at 4
X c
lock
fr
eque
ncy.
Doe
s no
t im
prov
e ef
ficie
ncy,
but
che
ap b
andw
idth
.S
uppo
rts
mor
e lo
ads
than
“o
rdin
ary
DD
R”,
so
mor
e ca
paci
ty.
Ken
tro
n Q
BM
TM
SWITCH
Co
ntr
olle
r
SWITCH
SWITCH
SWITCH
DD
R A
DD
R B
SWITCH
SWITCH
SWITCH
DD
R A
DD
R B
SWITCH
SWITCH
SWITCH
DD
R A
DD
R B
op
eno
pen
op
en
SWITCH
SWITCH
DD
R A
DD
R B
“Wra
pp
er E
lect
ron
ics
aro
un
d D
DR
mem
ory
”G
ener
ates
4 d
ata
bit
s p
er c
ycle
inst
ead
of
2.
Qu
ad B
and
Mem
oryd
1d
1d
1d
1
d0
d0
d0
d0
d1
d1
d1
d1
d0
d0
d0
d0
DD
R A
DD
R B
Ou
tpu
t
Clo
ck
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Inst
ead
of th
inin
g ab
out t
hing
s on
a s
tric
t lat
ency
-ban
dwid
th
pers
pect
ive,
it m
ight
be
mor
e he
lpfu
l to
thin
k in
term
s of
la
tenc
y vs
pin
-tra
nsiti
on
effic
ienc
y pe
rspe
ctiv
e. T
he id
ea
is th
at
A D
iffe
ren
t P
ersp
ecti
ve
Eve
ryth
ing
is b
and
wid
th
Lat
ency
an
d B
and
wid
th
Pin
-ban
dw
idth
an
d
Pin
-tra
nsi
tio
n *
Effi
cien
cy (
bit
s/cy
cle/
sec)
Clo
ck
Co
l. C
md
/Ad
dr
Ban
dw
idth
Wri
te D
ata
Ban
dw
idth
Rea
d D
ata
Ban
dw
idth
Ro
w C
md
/Ad
dr
Ban
dw
idth
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
DR
AM
sys
tem
s is
bas
ical
ly a
ne
twor
king
sys
tem
with
a s
mar
t m
aste
r co
ntro
ller
and
a la
rge
num
ber
of “d
umb”
sla
ve d
evic
es.
If w
e ar
e co
ncer
ned
abou
t “e
ffici
ency
” on
a bi
t/pin
/sec
leve
l, it
mig
ht b
ehoo
ve u
s to
dra
w
insp
iratio
n fr
om n
etw
ork
inte
rfac
es, a
nd d
esig
n so
met
hing
like
this
...
Uni
dire
ctio
n co
mm
and
and
writ
e pa
cket
s fr
om c
ontr
olle
r to
DR
AM
ch
ips,
and
Uni
dire
ctio
n bu
s fr
om
DR
AM
chi
ps b
ack
to th
e co
ntro
ller.
The
n it
look
s lik
e a
netw
ork
syst
em w
ith s
lot r
ing
inte
rfac
e, n
o ne
ed to
dea
l with
bu
s-tu
rn a
roun
d is
sues
.
Res
earc
h A
reas
: To
po
log
y
Un
idir
ecti
on
al T
op
olo
gy:
•W
rite
Pac
kets
sen
t o
n C
om
man
d B
us
•P
ins
use
d fo
r C
om
man
d/A
dd
ress
/Dat
a
•F
urt
her
Incr
ease
of
Lo
gic
on
DR
AM
ch
ips
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Cer
tain
thin
gs s
impl
y do
es n
ot
mak
e se
nse
to d
o. S
uch
as
vario
us S
TR
EA
M c
ompo
nent
s.
Mov
e m
ultim
egab
yte
arra
ys fr
om
DR
AM
to C
PU
, jus
t to
perf
orm
si
mpl
e “a
dd” f
unct
ion,
then
mov
e th
at m
ulti
meg
abyt
e ar
rays
rig
ht
back
. In
such
ext
rem
e ba
ndw
idth
con
stra
ined
ap
plic
atio
ns, i
t wou
ld b
e be
nefic
ial t
o ha
ve s
ome
logi
c or
ha
rdw
are
on D
RA
M c
hips
that
ca
n pe
rfor
m s
impl
e co
mpu
tatio
n. T
his
is tr
icky
, sin
ce
we
do n
ot w
ant t
o ad
d to
o m
uch
logi
c as
to m
ake
the
DR
AM
ch
ips
proh
ibat
ivel
y ex
pens
ive
to
man
ufac
ture
. (lo
gic
over
head
de
crea
ses
with
eac
h ge
nera
tion,
so
add
ing
logi
c is
not
an
impo
ssib
le d
ream
) A
lso,
we
do
not w
ant t
o ad
d lo
gic
into
the
criti
cal p
ath
of a
DR
AM
acc
ess.
T
hat w
ould
ser
ve to
slo
w d
own
a ge
nera
l acc
ess
in te
rms
of th
e “r
eal l
aten
cy”
in n
s.
Mem
ory
Co
mm
and
s?
Inst
ead
of
A[
] =
0; D
o “
wri
te 0
”
Wri
teA
ct
0000
00W
rite
0A
ct
Why
do
ST
RE
AM
add
in C
PU
?
A[
] =
B[
] +
C[
]
Act
ive
Pag
es *
(Ch
on
g e
t. al
. IS
CA
‘98)
Why
do
A[
] =
B[
] in
CP
U?
Mov
e D
ata
insi
de
of
DR
AM
or
bet
wee
n D
RA
Ms.
Mem
ory
Co
ntr
olle
r
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
For
a g
iven
phy
sica
l add
ress
, th
ere
are
a nu
mbe
r of
way
s to
m
ap th
e bi
ts o
f the
phy
sica
l ad
dres
s to
gen
erat
e th
e “m
emor
y ad
dres
s” in
term
s of
de
vice
ID, R
ow/c
ol a
ddr,
and
bank
id.
The
map
ping
pol
icie
s co
uld
impa
ct p
erfo
rman
ce, s
ince
bad
ly
map
ped
syst
ems
can
caus
e ba
nk c
onfli
cts
in c
onse
cutiv
e ac
cess
es.
Now
, map
ping
pol
icie
s m
ust a
lso
take
tem
pera
ture
con
trol
into
ac
coun
t, as
con
secu
tive
acce
sses
that
hit
the
sam
e D
RA
M c
hip
can
pote
ntia
lly
crea
te u
ndes
irabl
e ho
t spo
ts.
One
rea
son
for
the
addi
tiona
l co
st o
f RD
RA
M in
itial
ly w
as th
e us
e of
hea
t spr
eade
rs o
n th
e m
emor
y m
odul
es to
pre
vent
the
hots
pots
from
bui
ldin
g up
.
Ad
dre
ss M
app
ing
Acc
ess
Dis
trib
uti
on
for T
emp
Co
ntr
ol
Avo
id B
ank
Co
nfl
icts
Acc
ess
Reo
rder
ing
for
per
form
ance
Phy
sica
l A
dd
ress
Ro
w A
dd
rB
ank
IdC
ol A
dd
rD
evic
e Id
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Eac
h M
emor
y sy
stem
con
sist
s of
one
or
mor
e m
emor
y ch
ips,
an
d m
ost t
imes
, acc
esse
s to
th
ese
chip
s ca
n be
pip
elin
ed.
Eac
h ch
ip a
lso
has
mul
titud
es o
f ba
nks,
and
mos
t of t
he ti
mes
, ac
cess
es to
thes
e ba
nks
can
also
be
pipe
lined
. (ke
y to
ef
ficie
ncy
is to
pip
elin
e co
mm
ands
)
Exa
mp
le: B
ank
Co
nfl
icts
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
Mu
ltip
le B
anks
to R
edu
ce
Acc
ess
Co
nfl
icts
Rea
d 0
5AE
5700
Rea
d 0
23B
B88
0
Rea
d 0
0CB
A2C
0
Dev
ice
id 3
, Ro
w id
266
, Ban
k id
0D
evic
e id
3, R
ow
id 1
BA
, Ban
k id
0
Dev
ice
id 3
, Ro
w id
052
, Ban
k id
1R
ead
05A
E57
80D
evic
e id
3, R
ow
id 2
66, B
ank
id 0
Mo
re B
anks
per
Ch
ip =
= P
erfo
rman
ce =
= L
og
ic O
verh
ead
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Eac
h Lo
ad c
omm
and
is
tran
slat
ed to
a r
ow c
omm
and
and
a co
lum
n co
mm
and.
If tw
o co
mm
ands
are
map
ped
to th
e sa
me
bank
, one
mus
t be
com
plet
ed b
efor
e th
e ot
her
can
star
t.
Or,
if w
e ca
n re
-ord
er th
e se
quen
ces,
then
the
entir
e se
quen
ce c
an b
e co
mpl
eted
fa
ster
.
By
allo
win
g R
ead
3 to
byp
ass
Rea
d 2,
we
do n
ot n
eed
to
gene
rate
ano
ther
row
act
ivat
ion
com
man
d. R
ead
4 m
ay a
lso
bypa
ss R
ead
2, s
ince
it o
pera
tes
on a
diff
eren
t Dev
ice/
bank
en
tirel
y.D
RA
M n
ow c
an d
o au
to
prec
harg
e, b
ut I
put i
n th
e pr
echa
rge
expl
icitl
y to
sho
w th
at
two
row
s ca
nnot
be
activ
e w
ithin
tR
C (
DR
AM
arc
hite
ctur
e)
cons
trai
nts.
Exa
mp
le: A
cces
s R
eord
erin
gR
ead
05A
E57
00R
ead
023
BB
880
Rea
d 0
0CB
A2C
0
Dev
ice
id 3
, Ro
w id
266
, Ban
k id
0D
evic
e id
3, R
ow
id 1
BA
, Ban
k id
0
Dev
ice
id 1
, Ro
w id
052
, Ban
k id
1R
ead
05A
E57
80D
evic
e id
3, R
ow
id 2
66, B
ank
id 0
Rea
d
Act
Dat
a
Pre
c
Act
= A
ctiv
ate
Pag
e (D
ata
mov
ed f
rom
DR
AM
cel
ls t
o r
ow
bu
ffer
)R
ead
= R
ead
Dat
a (D
ata
mov
ed f
rom
ro
w b
uff
er t
o m
emo
ry c
on
tro
ller)
Pre
c =
Pre
char
ge
(clo
se p
age/
evic
t d
ata
in r
ow
bu
ffer
/sen
se a
mp
)
Rea
d
Act
Dat
a
Pre
c
1 2 3 4
Rea
d
Act
Dat
a
Rea
d
Act
Dat
a
Pre
c
Str
ict
Ord
erin
g
Rea
d
Act
Dat
a
Pre
c4
2
Rea
d
Act
Dat
a
Pre
c
3
112
3
Mem
ory
Acc
ess
Re-
ord
ered
t RC
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
now
--
talk
abo
ut p
erfo
rman
ce
issu
es.
Ou
tlin
e
•B
asic
s
•D
RA
M E
volu
tio
n: S
tru
ctu
ral P
ath
•A
dva
nce
d B
asic
s
•D
RA
M E
volu
tio
n: I
nte
rfac
e P
ath
•F
utu
re In
terf
ace
Tren
ds
& R
esea
rch
Are
as
•P
erfo
rman
ce M
od
elin
g:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Sim
ula
tor
Ove
rvie
w
CP
U: S
imp
leS
cala
r v3
.0a
•8-
way
ou
t-o
f-o
rder
•L
1 ca
che:
sp
lit 6
4K/6
4K, l
ock
up
fre
e x3
2
•L
2 ca
che:
un
ified
1M
B, l
ock
up
fre
e x1
•L
2 b
lock
size
: 128
byt
es
Mai
n M
emo
ry: 8
64M
b D
RA
Ms
•10
0MH
z/12
8-b
it m
emo
ry b
us
•O
pti
mis
tic
op
en-p
age
po
licy
Ben
chm
arks
: SP
EC
’95
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DR
AM
Co
nfi
gu
rati
on
s
No
te: T
RA
NS
FE
R W
IDT
H o
f D
irec
t R
ambu
s C
han
nel
•eq
ual
s th
at o
f g
ang
ed F
PM
, ED
O, e
tc.
•is
2x
that
of
Ram
bus
& S
LD
RA
M
CP
UM
emo
ry
Co
ntr
olle
ran
d c
ach
es
x16
DR
AM
x16
DR
AM
x16
DR
AM
x16
DR
AM
x16
DR
AM
x16
DR
AM
x16
DR
AM
x16
DR
AM
128-
bit
100
MH
z bu
s
DIM
M
FP
M, E
DO
, SD
RA
M, E
SD
RA
M, D
DR
:
Fast
, Nar
row
Ch
ann
el
CP
UM
emo
ry
Co
ntr
olle
ran
d c
ach
es12
8-b
it 1
00M
Hz
bus
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
Ram
bus,
Dir
ect
Ram
bus,
SL
DR
AM
:
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DR
AM
Co
nfi
gu
rati
on
s DRAM
DRAM
DRAM
DRAM
DRAM
... Mu
ltip
le P
aral
lel C
han
nel
s
CP
UM
emo
ry
Co
ntr
olle
ran
d c
ach
es12
8-b
it 1
00M
Hz
bus
Str
awm
an: R
ambu
s, e
tc.
Fast
, Nar
row
Ch
ann
el x
2
CP
Uan
d c
ach
es12
8-b
it 1
00M
Hz
bus
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
Ram
bus
& S
LD
RA
M d
ual
-ch
ann
el:
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAM
DRAMM
emo
ry
Co
ntr
olle
r
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Fir
st …
Ref
resh
Mat
ters
Ass
um
es r
efre
sh o
f ea
ch b
ank
ever
y 64
ms
FP
M1
FP
M2
FP
M3
ED
O1
ED
O2
SD
RA
M1
ES
DR
AM
SLD
RA
MR
DR
AM
DR
DR
AM
DR
AM
Con
figur
atio
ns0
400
800
1200
Time per Access (ns)
com
pre
ss
Bus
Tra
nsm
issi
on T
ime
Row
Acc
ess
Tim
eC
olum
n A
cces
s T
ime
Dat
a T
rans
fer
Tim
e O
verla
pD
ata
Tra
nsfe
r T
ime
Ref
resh
Tim
eB
us W
ait T
ime
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ove
rhea
d: M
emo
ry v
s. C
PU
Var
iab
le: s
pee
d o
f p
roce
sso
r &
cac
hes
Com
pres
sG
ccG
oIjp
egLi
M88
ksim
Per
lV
orte
x0
0.51
1.52
2.53
Clocks Per Instruction (CPI)
To
tal E
xecu
tio
n T
ime
in C
PI —
SD
RA
M
Pro
cess
or
Exe
cuti
on
(in
clu
des
cac
hes
)O
verl
ap b
etw
een
Exe
cuti
on
& M
emo
ryS
talls
du
e to
Mem
ory
Acc
ess
Tim
e
Yest
erda
y’s
CPU
Tom
orro
w’s
CPU
Toda
y’s
CPU
BE
NC
HM
AR
K
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Defi
nit
ion
s (v
ar. o
n B
urg
er, e
t al
)
•t P
RO
C —
pro
cess
or
wit
h p
erfe
ct m
emo
ry
•t R
EA
L —
rea
listi
c co
nfi
gu
rati
on
•t B
W —
CP
U w
ith
wid
e m
emo
ry p
ath
s
•t D
RA
M —
tim
e se
en b
y D
RA
M s
yste
m
Sta
lls D
ue
toB
AN
DW
IDT
H
Sta
lls D
ue
toL
AT
EN
CY
CP
U+L
1+L
2E
xecu
tio
n
CP
U-M
emo
ryO
VE
RL
AP
t DR
AM
t PR
OC
t BW
t RE
AL
t RE
AL
- t B
W
t BW
- t P
RO
C
t RE
AL
- t D
RA
M
t PR
OC
- (t
RE
AL
- t D
RA
M)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Mem
ory
& C
PU
— P
ER
L
Ban
dw
idth
-En
han
cin
g T
ech
niq
ues
I:
FP
ME
DO
DR
DR
AM
ES
DR
AM
DD
RS
LDR
AM
RD
RA
MS
DR
AM
012345
Cycles Per Instruction (CPI)
DR
AM
Co
nfi
gu
rati
on
Yeste
rday
’s CPU
Tomorro
w’s CPU
Today’s
CPU
Pro
cess
or
Exe
cuti
on
Ove
rlap
bet
wee
n E
xecu
tio
n &
Mem
ory
Sta
lls d
ue
to M
emo
ry L
aten
cyS
talls
du
e to
Mem
ory
Ban
dw
idth
New
er D
RA
Ms
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Mem
ory
& C
PU
— P
ER
L
Ban
dw
idth
-En
han
cin
g T
ech
niq
ues
II:
FP
M/in
terle
aved
ED
O/in
terle
aved
SD
RA
M &
DD
RS
LDR
AM
x1/
x2R
DR
AM
x1/
x2012345
Cycles Per Instruction (CPI)
Exe
cutio
n T
ime
in C
PI —
PE
RL
DR
AM
Co
nfi
gu
rati
on
(10
GH
z C
PU
s)
Pro
cess
or
Exe
cuti
on
Ove
rlap
bet
wee
n E
xecu
tio
n &
Mem
ory
Sta
lls d
ue
to M
emo
ry L
aten
cyS
talls
du
e to
Mem
ory
Ban
dw
idth
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ave
rag
e L
aten
cy o
f D
RA
Ms
no
te: S
LD
RA
M &
RD
RA
M 2
x d
ata
tran
sfer
s
0
100
200
300
400
500
Avg Time per Access (ns)
DR
AM
Co
nfi
gu
rati
on
s
Bu
s T
ran
smis
sio
n T
ime
Ro
w A
cces
s T
ime
Co
lum
n A
cces
s T
ime
Dat
a T
ran
sfer
Tim
e O
verl
apD
ata
Tra
nsf
er T
ime
Ref
resh
Tim
eB
us
Wai
t T
ime
FP
ME
DO
DR
DR
AM
ES
DR
AM
DD
RS
LDR
AM
RD
RA
MS
DR
AM
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ave
rag
e L
aten
cy o
f D
RA
Ms
no
te: S
LD
RA
M &
RD
RA
M 2
x d
ata
tran
sfer
s
0
100
200
300
400
500
Avg Time per Access (ns)
DR
AM
Co
nfi
gu
rati
on
s
Bu
s T
ran
smis
sio
n T
ime
Ro
w A
cces
s T
ime
Co
lum
n A
cces
s T
ime
Dat
a T
ran
sfer
Tim
e O
verl
apD
ata
Tra
nsf
er T
ime
Ref
resh
Tim
eB
us
Wai
t T
ime
FP
ME
DO
DR
DR
AM
ES
DR
AM
DD
RS
LDR
AM
RD
RA
MS
DR
AM
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DD
R2
Stu
dy
Res
ult
s
cc1
com
pres
s
goijp
egli
linea
r_w
alk
mpe
g2de
c
mpe
g2en
c
peg−
wit
perl
ran−
dom
_wa
stre
am
stre
am
_no_
un
0.51
1.52
2.53
Arc
hite
ctur
al C
ompa
rison
pc10
0
ddr1
33
drd
ddr2
ddr2
ems
ddr2
vc
Ben
chm
ark
Normalized Execution Time (DDR2)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DD
R2
Stu
dy
Res
ult
s
1 G
hz5
Ghz
10 G
hz0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Per
l Run
time
pc10
0
ddr1
33
drd
ddr2
ddr2
ems
ddr2
vc
Pro
cess
or F
requ
ency
Execution Time (Sec.)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ro
w-B
uff
er H
it R
ates
Co
mp
ress
Gcc
Go
Ijp
eg
Li
M8
8ksim
Pe
rlV
ort
ex
SP
EC
IN
T 9
5 B
en
ch
ma
rks
0
20
40
60
80
10
0
Hit rate in row buffers
1M
B L
2 C
ach
e
Acro
rea
dCo
mp
ress
Gcc
Go
Ne
tsca
pe
Pe
rlP
ho
tosh
op
Po
we
rpo
int
Win
wo
rd
ET
CH
Tra
ce
s0
20
40
60
80
10
0
Hit rate in row buffers
1M
B L
2 C
ach
e
Co
mp
ress
Gcc
Go
Ijp
eg
Li
M8
8ksim
Pe
rlV
ort
ex
SP
EC
IN
T 9
5 B
en
ch
ma
rks
0
20
40
60
80
10
0
Hit rate in row buffers
4M
B C
ach
e
Acro
rea
dCo
mp
ress
Gcc
Go
Ne
tsca
pe
Pe
rlP
ho
tosh
op
Po
we
rpo
int
Win
wo
rd
ET
CH
Tra
ce
s0
20
40
60
80
10
0
Hit rate in row buffers
4M
B L
2 C
ach
e
Co
mp
ress
Gcc
Go
Ijp
eg
Li
M8
8ksim
Pe
rlV
ort
ex
SP
EC
IN
T 9
5 B
en
ch
ma
rks
0
20
40
60
80
10
0
Hit rate in row buffers
No
L2
Ca
ch
e
Acro
rea
dCo
mp
ress
Gcc
Go
Ne
tsca
pe
Pe
rlP
ho
tosh
op
Po
we
rpo
int
Win
wo
rd
ET
CH
Tra
ce
s0
20
40
60
80
10
0
Hit rate in row buffers
No
L2
Ca
ch
eF
PM
DR
AM
ED
OD
RA
MS
DR
AM
ES
DR
AM
DD
RS
DR
AM
SL
DR
AM
RD
RA
MD
RD
RA
M
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ro
w-B
uff
er H
it R
ates
02
46
810
0
1000
0
2000
0
3000
0
4000
0
5000
0
02
46
810
0
200
400
600
800
1000
02
46
810
0
5000
0
1e+
05
1.5e
+05
2e+
05
02
46
810
050100
150
200
02
46
810
0
1e+
05
2e+
05
3e+
05
4e+
05
02
46
810
0
5000
0
1e+
05
1.5e
+05
Co
mp
ress
Go
Ijpeg
Li
Per
l
Vo
rtex
Hit
s vs
. Dep
th in
Vic
tim
-Ro
w F
IFO
Bu
ffer
2000
4000
6000
8000
1000
0
Inte
r-ar
riva
l tim
e (C
PU
Clo
cks)
110100
1000
1000
0
1000
00
Co
mp
ress
2000
4000
6000
8000
1000
0
Inte
r-ar
riva
l tim
e (C
PU
Clo
cks)
110100
1000
1000
0V
ort
ex
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ro
w B
uff
ers
as L
2 C
ach
e
Com
pres
sG
ccG
oIjp
egLi
M88
ksim
Per
lV
orte
x01020
Clocks Per Instruction (CPI)
Pro
cess
or E
xecu
tion
Ove
rlap
betw
een
Exe
cutio
n &
Mem
ory
Sta
lls d
ue to
Mem
ory
Late
ncy
Sta
lls d
ue to
Mem
ory
Ban
dwid
th
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Eac
h m
emor
y tr
ansa
ctio
n ha
s to
br
eak
dow
n in
to a
two
part
ac
cess
, a r
ow a
cces
s an
d a
colu
mn
acce
ss. I
n es
senc
e th
e ro
w b
uffe
r/se
ns a
mp
is a
ctio
n as
a
cach
e. w
here
a p
age
is
brou
ght i
n fr
om th
e m
emor
y ar
ray
and
stor
ed in
the
buffe
r th
en th
e se
cond
ste
p is
to m
ove
that
dat
a fr
om th
e ro
w b
uffe
rs
back
into
the
mem
ory
cont
rolle
r. fr
om a
cer
tain
per
spec
tive,
it
mak
es s
ense
to s
pecu
lativ
ely
mov
e pa
ges
from
mem
ory
arra
ys in
to th
e ro
w b
uffe
rs to
m
axim
ize
the
page
hit
of a
co
lum
n ac
cess
, and
red
uce
late
ncy.
The
cos
t of a
sp
ecul
ativ
e ro
w a
ctiv
atio
n co
mm
and
is th
e ~
20 b
it of
ba
ndw
idth
sen
t on
the
com
man
d ch
anne
l fro
m c
ontr
olle
r to
D
RA
M. i
nste
ad o
f pre
fetc
hing
in
to D
RA
M, w
e’re
just
pr
efet
chin
g in
side
of D
RA
M.
Row
buf
fer
hit r
ates
40~
90%
, de
pend
ing
on a
pplic
atio
n.
*cou
ld*
be n
ear 1
00%
if m
emor
y sy
stem
get
s sp
ecul
ativ
e ro
w
buffe
r m
anag
emen
t com
man
ds.
(Thi
s on
ly m
akes
sen
se if
m
emor
y co
ntro
ller
is in
tegr
ated
)
Ro
w B
uff
er M
anag
emen
t
RA
S is
like
Cac
he
Acc
ess
Why
no
t S
pec
ula
te?
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
Dat
a In
/Ou
tB
uff
ers
RA
S
RO
W A
CC
ES
S
... B
it L
ines
...
Mem
ory
Arr
ay
Sen
se A
mp
s
Row Decoder
Co
lum
n D
eco
der
. . . .
Dat
a In
/Ou
tB
uff
ers
CA
S
CO
LU
MN
AC
CE
SS
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Co
st-P
erfo
rman
ce
FP
M, E
DO
, SD
RA
M, E
SD
RA
M:
•L
ow
er L
aten
cy =
> W
ide/
Fast
Bu
s
•In
crea
se C
apac
ity
=> D
ecre
ase
Lat
ency
•L
ow
Sys
tem
Co
st
Ram
bus,
Dir
ect
Ram
bus,
SL
DR
AM
:
•L
ow
er L
aten
cy =
> M
ult
iple
Ch
ann
els
•In
crea
se C
apac
ity
=> In
crea
se C
apac
ity
•H
igh
Sys
tem
Co
st
Ho
wev
er, 1
DR
DR
AM
= M
ult
iple
SD
RA
M
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Co
ncl
usi
on
s
100M
Hz/
128-
bit
Bu
s is
Cu
rren
t B
ott
len
eck
•S
olu
tio
n: F
ast
Bu
s/es
& M
C o
n C
PU
(e
.g. A
lph
a 21
364,
Em
oti
on
En
gin
e, …
)
Cu
rren
t D
RA
Ms
So
lvin
g B
and
wid
th P
rob
lem
(b
ut
no
t L
aten
cy P
rob
lem
)
•S
olu
tio
n: N
ew c
ore
s w
ith
on
-ch
ip S
RA
M(e
.g. E
SD
RA
M, V
CD
RA
M, …
)
•S
olu
tio
n: N
ew c
ore
s w
ith
sm
alle
r b
anks
(e.g
. Mo
Sys
“S
RA
M”,
FC
RA
M, …
)
Dir
ect
Ram
bus
seem
s to
sca
le b
est
for
futu
re
hig
h-s
pee
d C
PU
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
now
--
let’s
talk
abo
ut D
RA
M
perf
orm
ance
at t
heS
YS
TE
M
leve
l.
prev
ious
stu
dies
sho
w
ME
MO
RY
BU
S is
sig
nific
ant
bottl
enec
k in
toda
y’s
high
-pe
rfor
man
ce s
yste
ms
- S
chum
ann
repo
rts
that
in
Alp
ha w
orks
tatio
ns, 3
0-60
% o
f P
RIM
AR
Y M
EM
OR
Y L
ATE
NC
Y,
is d
ue to
SY
ST
EM
OV
ER
HE
AD
ot
her
than
DR
AM
late
ncy
- H
arva
rd s
tudy
cite
s B
US
T
UR
NA
RO
UN
D a
s re
spon
sibl
e fo
r fa
ctor
-of-
two
diffe
renc
e be
twee
n P
RE
DIC
TE
D a
nd
ME
AS
UR
ED
per
form
ance
in P
6 sy
stem
s
- ou
r pr
evio
us w
ork
show
s to
day’
s bu
sses
(19
99’s
bus
ses)
ar
e bo
ttlen
ecks
for
tom
orro
w’s
D
RA
Ms
so -
- lo
ok a
t bus
, mod
el s
yste
m
over
head
Ou
tlin
e
•B
asic
s
•D
RA
M E
volu
tio
n: S
tru
ctu
ral P
ath
•A
dva
nce
d B
asic
s
•D
RA
M E
volu
tio
n: I
nte
rfac
e P
ath
•F
utu
re In
terf
ace
Tren
ds
& R
esea
rch
Are
as
•P
erfo
rman
ce M
od
elin
g:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
at th
e S
YS
TE
M L
EV
EL
-- i.
e.
outs
ide
the
CP
U -
- w
e fin
d a
larg
e nu
mbe
r of
par
amet
ers
this
stu
dy o
nly
VA
RIE
S a
ha
ndfu
l, bu
t it s
till y
ield
s a
fairl
y la
rge
spac
e
the
para
met
ers
we
VA
RY
are
in
blue
& g
reen
by “
part
ially
” ind
epen
dent
, i
mea
n th
at w
e lo
oked
at a
sm
all
num
ber
of p
ossi
bilit
ies:
- tu
rnar
ound
is 0
/1 c
ycle
on
800M
Hz
bus
- re
ques
t ord
erin
g is
IN
TE
RLE
AV
ED
or
NO
T
Mo
tiva
tio
n
Eve
n w
hen
we
rest
rict
ou
r fo
cus
…
SY
ST
EM
-LE
VE
L P
AR
AM
ET
ER
S
•N
um
ber
of
chan
nel
sW
idth
of
chan
nel
s•
Ch
ann
el la
ten
cyC
han
nel
ban
dw
idth
•B
anks
per
ch
ann
elTu
rnar
ou
nd
tim
e•
Req
ues
t-q
ueu
e si
zeR
equ
est
reo
rder
ing
•
Ro
w-a
cces
sC
olu
mn
-acc
ess
•D
RA
M p
rech
arg
eC
AS
-to
-CA
S la
ten
cy•
DR
AM
bu
ffer
ing
L2
cach
e b
lock
size
•N
um
ber
of
MS
HR
sB
us
pro
toco
l
Fu
lly |
par
tial
ly |
no
t in
dep
end
ent
(th
is s
tud
y)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
and
yet,
even
in th
is r
estr
icte
d de
sign
spa
ce, w
e fin
d hi
ghly
E
XT
RE
ME
LY C
OM
PLE
X r
esul
ts
SY
ST
EM
is v
ery
SE
NS
ITIV
E to
C
HA
NG
ES
in th
ese
para
met
ers
[dis
cuss
gra
ph]
if yo
u ho
ld a
ll el
se c
onst
ant a
nd
vary
one
par
amet
er, y
ou c
an
see
extr
emel
y la
rge
chan
ges
in
end
perf
orm
ance
... u
p to
40%
di
ffere
nce
by c
hang
ing
ON
E
PAR
AM
ET
ER
by
a FA
CTO
R O
F
TW
O (
e.g.
dou
blin
g th
e nu
mbe
r of
ban
ks, d
oubl
ing
the
size
of t
he
burs
t, do
ublin
g th
e nu
mbe
r of
ch
anne
ls, e
tc.)
Mo
tiva
tio
n
... t
he
des
ign
sp
ace
is h
igh
ly n
on
-lin
ear
…
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dwid
th
0123
Cycles per Instruction (CPI)
(GB
/s =
Cha
nnel
s *
Wid
th *
800
MH
z)
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
GC
C12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
so -
- w
e ha
ve th
e w
orst
pos
sibl
e sc
enar
io: a
des
ign
spac
e th
at is
ve
ry s
ensi
tive
to c
hang
es in
pa
ram
eter
s an
d ex
ecut
ion
times
th
at c
an v
ary
by a
FA
CTO
R O
F
TH
RE
E fr
om w
orst
-cas
e to
bes
t
clea
rly, w
e w
ould
be
wel
l-ser
ved
to u
nder
stan
d th
is d
esig
n sp
ace
Mo
tiva
tio
n
... a
nd
th
e co
st o
f p
oo
r ju
dg
men
t is
hig
h.
bzi
pg
ccm
cfp
arse
rp
erl
vpr
aver
age
SP
EC
200
0 B
ench
mar
ks
0246810 Cycles per Instruction (CPI)
Bes
t O
rgan
izat
ion
Ave
rag
e O
rgan
izat
ion
Wo
rst
Org
aniz
atio
n
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
so b
y no
w w
e’re
ver
y fa
mili
ar
with
this
pic
ture
...
we
cann
ot u
se it
in th
is s
tudy
, be
caus
e th
is r
epre
sent
s th
e in
terf
ace
betw
een
the
DR
AM
an
d th
e M
EM
OR
Y
CO
NT
RO
LLE
R.
typi
cally
, the
CP
U’s
inte
rfac
e is
m
uch
sim
pler
: the
CP
U s
ends
all
of th
e ad
dres
s bi
ts a
t onc
e w
ith
CO
NT
RO
L IN
FO
(r/
w),
and
the
mem
ory
cont
rolle
r ha
ndle
s th
e bi
t add
ress
ing
and
the
RA
S/C
AS
tim
ing
Sys
tem
-Lev
el M
od
el
SD
RA
M T
imin
g
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
DD
ata
Tran
sfer
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
this
giv
es th
e pi
ctur
e of
wha
t is
happ
enin
g at
the
SY
TE
M
LEV
EL
the
CP
U to
ME
M
CO
NT
RO
LLE
R is
sho
wn
as
“AB
US
Act
ive”
the
ME
M-C
ON
TR
OLL
ER
to
DR
AM
act
ivity
is s
how
n as
D
RA
M B
AN
K A
CT
IVE
and
the
data
rea
d-ou
t is
show
n as
“D
BU
S A
ctiv
e”
i
Sys
tem
-Lev
el M
od
el
Tim
ing
dia
gra
ms
are
at t
he
DR
AM
leve
l…
no
t th
e sy
stem
leve
l
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
DD
ata
Tran
sfer
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
Ban
k A
ctiv
e
DB
US
Act
ive
AB
US
Act
ive
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
f the
DR
AM
’s p
ins
do n
ot
conn
ect d
irect
ly to
the
CP
U (
e.g.
in
a h
iera
rchi
cal b
us
orga
niza
tion,
or
if th
e da
ta is
fu
nnel
led
thro
ugh
the
mem
ory
cont
rolle
r lik
e th
e no
rthb
ridge
ch
ipse
t), t
hen
ther
e is
yet
an
othe
r D
BU
S A
CT
IVE
tim
ing
slot
that
follo
ws
belo
w a
nd to
the
right
... t
his
can
cont
inue
to
exte
nd to
any
num
ber
of
hier
arch
ical
leve
ls, a
s se
en in
hu
ge s
erve
r sy
stem
s w
ith
hund
reds
of G
B o
f DR
AM
Sys
tem
-Lev
el M
od
el
Tim
ing
dia
gra
ms
are
at t
he
DR
AM
leve
l…
no
t th
e sy
stem
leve
l
Co
mm
and
Ad
dre
ss
DQ
Clo
ck Ro
wA
dd
rC
ol
Ad
dr
Val
idD
ata
Val
idD
ata
Val
idD
ata
Val
idD
ata
AC
TR
EA
DD
ata
Tran
sfer
Co
lum
n A
cces
s
Tran
sfer
Ove
rlap
Ro
w A
cces
s
DR
AM
Ban
k A
ctiv
e
DB
US
1 A
ctiv
eA
BU
S A
ctiv
e
DB
US
2 A
ctiv
e
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
so le
t’s fo
rmal
ize
this
sys
tem
-le
vel i
nter
face
. her
e’s
the
requ
est t
imin
g in
a s
light
ly
diffe
rent
way
, as
wel
l as
an
exam
ple
syst
em m
odel
take
n fr
om s
chum
ann’
s pa
per
desc
ribin
g th
e 21
174
mem
ory
cont
rolle
r
the
DR
AM
’s d
ata
pins
are
co
nnec
ted
dire
ctly
to th
e C
PU
(s
impl
est p
ossi
ble
mod
el),
the
mem
ory
cont
rolle
r ha
ndle
s th
e R
AS
/CA
S ti
min
g, a
nd th
e C
PU
an
d m
emor
y co
ntro
ller
only
talk
in
term
s of
add
ress
es a
nd
cont
rol i
nfor
mat
ion
Req
ues
t Tim
ing
CP
UC
ach
e
MC
DRAM
DRAM
DRAM
DRAM
Bac
ksid
e bu
sF
ron
tsid
e bu
s
Dat
a bu
s (8
00 M
Hz) R
ow
/Co
lum
n A
dd
ress
es &
Co
ntr
ol
Ad
dre
ss
Co
ntr
ol
Ad
dre
ss
Dat
a bu
s t 0
<DB
0><D
B1>
<DB
2><D
B3>
DA
TA B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
RE
AD
RE
QU
ES
T T
IMIN
G: <R
OW
>
<
CO
L>
<P
RE
>
(800
MH
z)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
such
a m
odel
giv
es u
s th
ese
type
s of
req
uest
sha
pes
for
read
s an
d w
rites
this
sho
ws
a fe
w e
xam
ple
bus/
burs
t con
figur
aito
ns, i
n pa
rtic
ular
:
4-by
te b
us w
ith b
urst
siz
es o
f 32,
64
, and
128
byt
es p
er b
urst
Rea
d/W
rite
Req
ues
t S
hap
es
t
0
10n
s90
ns
DAT
A B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
70n
s
RE
AD
RE
QU
ES
TS
:
DAT
A B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
20n
s90
ns
70n
s
DAT
A B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
40n
s10
0ns
70n
s
t
0
10
ns
10n
s90
ns
D
ATA
BU
S
AD
DR
ES
S B
US
DR
AM
BA
NK
40
ns
WR
ITE
RE
QU
ES
TS
:
DAT
A B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
20n
s
10n
s90
ns
40n
s
DAT
A B
US
AD
DR
ES
S B
US
DR
AM
BA
NK
40n
s
10n
s90
ns
40n
s
10n
s
10n
s
10n
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
the
bus
is P
IPE
LIN
ED
and
su
ppor
ts S
PLI
T
TR
AN
SA
CT
ION
S w
here
one
re
ques
t can
be
NE
ST
LED
insi
de
of a
noth
er if
the
timin
g is
rig
ht
[exp
lain
exa
mpl
es]
wha
t we’
re tr
ying
to d
o is
to fi
t th
ese
2D p
uzzl
e pi
eces
toge
ther
in
TIM
E
Pip
elin
ed/S
plit
Tra
nsa
ctio
ns
Nes
tling
of w
rites
insi
de r
eads
is le
gal i
f R/W
to d
iffer
ent b
anks
:
Leg
al if
R/R
to d
iffer
ent b
anks
:
(a)
(b)
(c)
B
ack-
to-b
ack
R/W
pai
r th
at c
anno
t be
nest
led:
Leg
al if
turn
arou
nd <
= 1
0ns:
20ns
10ns
90ns
70ns
20ns
10ns
90ns
40ns
20ns
10ns
90ns
70ns
Leg
al if
no
turn
arou
nd:
Read
:
Writ
e:
10ns
10ns
90ns
40ns
10ns
10ns
90ns
70ns
Read
:
Writ
e:
20ns
10ns
90ns
70ns
Read
:
Read
:
20ns
1010
40ns
10ns
90ns
40ns
40ns
10ns
100n
s
70ns
Read
:
Writ
e:
10
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
as fo
r phy
sica
l con
nect
ions
, her
e ar
e th
e w
ays
we
mod
eled
in
depe
nden
t DR
AM
cha
nnel
s an
d in
depe
nden
t BA
NK
S p
er
CH
AN
NE
L
the
figur
e sh
ows
a fe
w o
f the
pa
ram
eter
s th
at w
e st
udy.
in
addi
tion,
we
look
at:
- tu
rnar
ound
tim
e (0
,1 c
ycle
)
- qu
eue
size
(0,
1, 2
, 4, 8
, 16,
32
, infi
nite
req
uest
s pe
r ch
anne
l)
Ch
ann
els
& B
anks
1, 2
, 480
0 M
Hz
Ch
ann
els
8, 1
6, 3
2, 6
4D
ata
Bit
s p
er C
han
nel
1, 2
, 4, 8
Ban
ks p
er C
han
nel
(In
dep
.)32
, 64,
128
Byt
es p
er B
urs
t
C
D
C
DD
C
DD
DD
D
CD
C
DD
DD
C
DD
DD
DD
DD
C
DD
DD
DD
DD
DD
DD
DD
DD
C
DD
DD
DD
DD
C
DD
DD
...
... ...
On
e in
dep
end
ent
chan
nel
Ban
kin
g d
egre
es o
f 1,
2, 4
, ...
Fo
ur
ind
epen
den
t ch
ann
els
Ban
kin
g d
egre
es o
f 1,
2, 4
, ...
Two
ind
epen
den
t ch
ann
els
Ban
kin
g d
egre
es o
f 1,
2, 4
, ...
C
DD
C
DD
DD
CD
C
DD
C
DD
DD
C
DD
DD
DD
DD
C
DD
DD
DD
DD
DD
DD
DD
DD
C
DD
DD
DD
DD
C
DD
DD
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
how
do
you
chun
k up
a c
ache
bl
ock?
(L@
cac
hes
use
128-
byte
blo
cks)
[rea
d th
e bu
llets
]
LON
GE
R B
UR
ST
S a
mor
tize
the
cost
of a
ctiv
atin
g an
d pr
echa
rgin
g th
e ro
w o
ver
mor
e da
ta tr
ansf
erre
d
SH
OR
TE
R B
UR
ST
S a
llow
the
criti
cal w
ord
of a
FO
LLO
WIN
G
RE
QU
ES
T to
be
serv
iced
so
oner
so -
- th
is is
not
nov
el, b
ut it
is
fairl
y ag
gres
sive
NO
TE
: we
use
clos
e-pa
ge,
auto
prec
harg
e po
licy
with
E
SD
RA
M-s
tyle
buf
ferin
g of
R
OW
in S
RA
M. r
esul
t: ge
t the
be
st p
ossi
ble
prec
harg
e ov
erla
p A
ND
mul
tiple
bur
st r
eque
sts
to
the
sam
e ro
w w
ill n
ot re
-invo
ke a
R
AS
cyc
le u
nlea
ss a
n in
terv
enin
g R
EA
D r
eque
st g
oes
to a
diff
eren
t RO
W in
sam
e B
AN
K
Bu
rst
Sch
edu
ling
(Bac
k-to
-Bac
k R
ead
Req
ues
ts)
•
Cri
tica
l-bu
rst-
firs
t
•
No
n-c
riti
cal b
urs
ts a
re p
rom
ote
d
•
Wri
tes
hav
e lo
wes
t p
rio
rity
(t
end
bac
k u
p in
req
ues
t q
ueu
e …
)
•
Ten
sio
n b
etw
een
larg
e &
sm
all b
urs
ts:
amo
rtiz
atio
n v
s. f
aste
r ti
me
to d
ata
128-
Byt
e B
urs
ts:
64-B
yte
Bu
rsts
:
32-B
yte
Bu
rsts
:
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
f
Mar
ylan
d
we
run
a se
ries
of d
iffer
ent
sim
ulat
ions
to g
et b
reak
-dow
ns:
- C
PU
Act
ivity
- m
emor
y ac
tivity
ove
rlapp
ed
with
CP
U-
non-
over
lapp
ed -
SY
ST
EM
- no
n-ov
erla
pped
- d
ue to
DR
AM
so th
e to
p tw
o ar
e M
EM
OR
Y
STA
LL C
YC
LES
botto
m tw
o ar
e P
ER
FE
CT
M
EM
OR
Y
Not
e: M
EM
OR
Y L
ATE
NC
Y is
no
t fur
ther
div
ided
into
late
ncy/
band
wid
th/e
tc.
New
Bar
-Ch
art
Defi
nit
ion
•
t
PR
OC
— C
PU
wit
h 1
-cyc
le L
2 m
iss
•
t RE
AL —
rea
listi
c C
PU
/DR
AM
co
nfi
g
•t S
YS —
CP
U w
ith
1-c
ycle
DR
AM
late
ncy
•t D
RA
M —
tim
e se
en b
y D
RA
M s
yste
m
Sta
lls D
ue
toD
RA
M L
aten
cy
Sta
lls D
ue
toQ
ueu
e, B
us,
...
CP
U+L
1+L
2E
xecu
tio
n
CP
U-M
emo
ryO
VE
RL
AP
t DR
AM
t PR
OC
t SY
S
t RE
AL
t RE
AL
- t B
W
t SY
S -
t PR
OC
t RE
AL
- t D
RA
M
t PR
OC
- (t
RE
AL
- t D
RA
M)
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
so -
- w
e’re
mod
elin
g a
mem
ory
syst
em th
at is
fairl
y ag
gres
sive
in
term
s of
-
sche
dulin
g po
licie
s-
supp
ort f
or c
oncu
rren
cy
and
we’
re tr
ying
to fi
nd w
hich
of
the
follo
win
g is
to b
lam
e fo
r th
e m
ost o
verh
ead:
- co
ncur
renc
y-
late
ncy
- sy
stem
(qu
euei
ng, p
rech
arge
, ch
unks
, etc
)
Sys
tem
Ove
rhea
d
1.6
3.2
6.4
Sys
tem
Ban
dwid
th(G
B/s
= C
hann
els
* W
idth
* S
peed
)
1 ba
nk/ch
anne
l
2 ba
nks/c
hann
el
4 ba
nks/c
hann
el
8 ba
nks/c
hann
el 1 ba
nk/c
hann
el
2 ba
nks/
chan
nel
4 ba
nks/
chan
nel
8 ba
nks/
chan
nel 1 ba
nk/c
hann
el
2 ba
nks/
chan
nel
4 ba
nks/
chan
nel
8 ba
nks/
chan
nel
0123
0-C
ycle
Bus
Tur
naro
und
Reg
ular
Bus
Org
aniz
atio
n
Cycles per Instruction (CPI)
Per
fect
Mem
ory
Ben
chm
ark
= B
ZIP
(S
PE
C 2
000)
, 32-
byt
e b
urs
t, 1
6-b
it b
us
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
the
figur
e sh
ows:
- sy
stem
ove
rhea
d is
sig
nific
ant
(usu
ally
20-
40%
of t
he to
tal
mem
ory
over
head
)
- th
e m
ost s
igni
fican
t ove
rhea
d te
nds
to b
e th
e D
RA
M la
tenc
y
- tu
rnar
ound
is r
elat
ivel
y in
sign
ifica
nt (
how
ever
, re
mem
ber
that
this
is a
n 80
0MH
z bu
s sy
stem
...)
Sys
tem
Ove
rhea
d
1.6
3.2
6.4
Sys
tem
Ban
dwid
th(G
B/s
= C
hann
els
* W
idth
* S
peed
)
1 ba
nk/ch
anne
l
2 ba
nks/c
hann
el
4 ba
nks/c
hann
el
8 ba
nks/c
hann
el 1 ba
nk/c
hann
el
2 ba
nks/
chan
nel
4 ba
nks/
chan
nel
8 ba
nks/
chan
nel 1 ba
nk/c
hann
el
2 ba
nks/
chan
nel
4 ba
nks/
chan
nel
8 ba
nks/
chan
nel
0123
0-C
ycle
Bus
Tur
naro
und
Reg
ular
Bus
Org
aniz
atio
n
Cycles per Instruction (CPI)
Ben
chm
ark
= B
ZIP
(S
PE
C 2
000)
, 32-
byt
e b
urs
t, 1
6-b
it b
us
Sys
tem
ove
rhea
d 1
0–10
0%o
ver
per
fect
mem
ory
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
the
figur
e al
so s
how
s th
at
incr
easi
ng B
AN
KS
PE
R
CH
AN
NE
L gi
ves
you
alm
ost a
s m
uch
bene
fit a
s in
crea
sing
C
HA
NN
EL
BA
ND
WID
TH
, whi
ch
is m
uch
mor
e co
stly
to
impl
emen
t
=>
cle
arly
, the
re a
re s
ome
conc
urre
ncy
effe
cts
goin
g on
, an
d w
e’d
like
to q
uant
ify a
nd
bette
r un
ders
tand
them
Co
ncu
rren
cy E
ffec
ts
Ban
ks/c
han
nel
as
sig
nifi
can
t as
ch
ann
el B
W
1.6
3.2
6.4
Sys
tem
Ban
dwid
th(G
B/s
= C
hann
els
* W
idth
* S
peed
)
0123
Cycles per Instruction (CPI)
Ben
chm
ark
= B
ZIP
(S
PE
C 2
000)
, 32-
byt
e b
urs
t, 1
6-b
it b
us
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
BA
NK
S p
er C
HA
NN
EL
CH
AN
NE
L B
AN
DW
IDT
H
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
take
a lo
ok a
t a la
rger
por
tion
of
the
desi
gn s
pace
x-ax
is: S
YS
TE
M B
AN
DW
IDT
H,
whi
ch =
= c
hann
els
X c
hann
el
wid
th X
800
MH
z
y-ax
is: e
xecu
tion
time
of
appl
icat
ion
on th
e gi
ven
confi
gura
tion
diffe
rent
col
ored
bar
s re
pres
ent
diffe
rent
bur
st w
idth
s
ME
MO
RY
OV
ER
HE
AD
is
subs
tant
ial
obvi
ous
tren
d: m
ore
band
wid
th
is b
ette
r
anot
her
obvi
ous
tren
d: m
ore
band
wid
th is
NO
T
NE
CE
SS
AR
ILY
bet
ter
...
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
so -
- th
ere
are
som
e ob
viou
s tr
ade-
offs
rel
ated
to B
UR
ST
S
IZE
, whi
ch c
an a
ffect
the
TOTA
L E
XE
CU
TIO
N T
IME
by
30%
or
mor
e, k
eepi
ng a
ll el
se
cons
tant
.
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
if w
e lo
ok m
ore
clos
ely
at
indi
vidu
al s
yste
m o
rgan
izat
ions
, th
ere
are
som
e cl
ear
RU
LES
of
TH
UM
Bth
at a
pear
...
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
for
one,
LA
RG
E B
UR
ST
S a
re
optim
al fo
r WID
ER
CH
AN
NE
LS
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
Wid
e ch
ann
els
(32/
64-b
it)
wan
t la
rge
bu
rsts
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
for
anot
her,
SM
ALL
BU
RS
TS
ar
e op
timal
for
NA
RR
OW
C
HA
NN
ELS
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
Nar
row
ch
ann
els
(8-b
it)
wan
t sm
all b
urs
ts
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
and
ME
DIU
M B
UR
ST
S a
re
optim
al fo
r M
ED
IUM
C
HA
NN
ELS
so -
- if
CO
NC
UR
RE
NC
Y w
ere
all-i
mpo
rtan
t, w
e w
ould
exp
ect
smal
l bur
sts
to b
e be
st, b
ecau
se
they
wou
ld a
llow
a L
OW
ER
A
VE
RA
GE
TIM
E-T
O-C
RIT
ICA
L-W
OR
D fo
r a
larg
er n
umbe
r of
si
mul
tane
ous
requ
ests
.
wha
t we
actu
ally
see
is th
at th
e op
timal
bur
st w
idth
sca
lies
with
th
e bu
s w
idth
, sug
estin
g an
op
timal
num
ber
of D
ATA
T
RA
NS
FE
RS
per
BA
NK
A
CT
IVAT
ION
/PR
EC
HA
RG
E
cycl
e
i’ll i
llust
rate
that
...
Ban
dw
idth
vs.
Bu
rst W
idth
0.8
1.6
3.2
6.4
12.8
25.6
Sys
tem
Ban
dw
idth
0123
Cycles per Instruction (CPI)
(GB
/s =
Ch
ann
els
* W
idth
* 8
00M
Hz)12
8-B
yte
Bu
rst
64-B
yte
Bu
rst
32-B
yte
Bu
rst
Ben
chm
ark
= G
CC
(S
PE
C 2
000)
, 2 b
anks
/ch
ann
el
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 8
byt
es
2 ch
an x
4 b
ytes
4 ch
an x
2 b
ytes 2
chan
x 8
byt
es
4 ch
an x
4 b
ytes
4 ch
an x
8 b
ytes
1 ch
an x
2 b
ytes
2 ch
an x
1 b
yte
1 ch
an x
1 b
yte
Med
ium
ch
ann
els
(16-
bit
)w
ant
med
ium
bu
rsts
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
this
figu
re s
how
s th
e en
tire
rang
e of
bur
st w
idth
s th
at w
e m
odel
ed. n
ote
that
som
e of
the
figur
e re
pres
ent s
ever
al d
iffer
ent
com
bina
tions
... f
or e
xam
ple,
the
one
TH
IRD
DO
WN
FR
OM
TO
P
is
2-bu
te c
hann
el +
32-
byte
bur
st4-
byte
cha
nnel
+ 6
4-by
te b
urst
8-by
te c
hann
el +
128
-byt
e bu
rst
Bu
rst W
idth
Sca
les
wit
h B
us
Ran
ge
of
Bu
rst-
Wid
ths
Mo
del
ed
10ns
10ns
90ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
20ns
10ns
90ns
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
40ns
10ns
100n
s
70ns
5ns
10ns
90ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
80ns
10ns
140n
s
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
160n
s
10ns
220n
s
70ns
64-b
it ch
anne
l x 3
2-by
te b
urst
32-b
it ch
anne
l x 3
2-by
te b
urst
64-b
it ch
anne
l x 6
4-by
te b
urst
32-b
it ch
anne
l x 6
4-by
te b
urst
64-b
it ch
anne
l x 1
28-b
yte
burs
t
16-b
it ch
anne
l x 3
2-by
te b
urst
16-b
it ch
anne
l x 6
4-by
te b
urst
32-b
it ch
anne
l x 1
28-b
yte
burs
t
8-bi
t cha
nnel
x 3
2-by
te b
urst
16-b
it ch
anne
l x 1
28-b
yte
burs
t8-
bit c
hann
el x
64-
byte
bur
st
8-bi
t cha
nnel
x 1
28-b
yte
burs
t
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
the
optim
al c
onfig
urat
ions
are
in
the
mid
dle,
sug
gest
ing
an
optim
al n
umbe
r of
DAT
A
TR
AN
SF
ER
S p
er B
AN
K
AC
TIV
ATIO
N/P
RE
CH
AR
GE
cy
cle
[BO
TTO
M] -
- to
o m
any
tran
sfer
s pe
r bu
rst c
row
ds o
ut o
ther
re
ques
ts
[TO
P] -
- to
o fe
w tr
ansf
ers
per
requ
est l
ets
the
bank
ove
rhea
d (a
ctiv
atio
n/pr
echa
rge
cycl
e)
dom
inat
e
how
ever
, tho
ugh
this
tells
us
how
to b
est o
rgan
ize
a ch
anne
l w
ith a
giv
en b
andw
idth
, the
se
rule
s of
thum
b do
not
say
an
ythi
ng a
bout
how
the
diffe
rent
co
nfigu
ratio
ns (
wid
e/na
rrow
/m
ediu
m c
hann
els)
com
pare
to
each
oth
er ..
.
so le
t’s fo
cus
on m
ultip
le
confi
gura
tions
for
ON
E
BA
ND
WID
TH
CLA
SS
...
Bu
rst W
idth
Sca
les
wit
h B
us
Ran
ge
of
Bu
rst-
Wid
ths
Mo
del
ed
10ns
10ns
90ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
20ns
10ns
90ns
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
40ns
10ns
100n
s
70ns
5ns
10ns
90ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
80ns
10ns
140n
s
70ns
DATA
BUS
ADDR
ESS
BUS
DRAM
BAN
K
160n
s
10ns
220n
s
70ns
64-b
it ch
anne
l x 3
2-by
te b
urst
32-b
it ch
anne
l x 3
2-by
te b
urst
64-b
it ch
anne
l x 6
4-by
te b
urst
32-b
it ch
anne
l x 6
4-by
te b
urst
64-b
it ch
anne
l x 1
28-b
yte
burs
t
16-b
it ch
anne
l x 3
2-by
te b
urst
16-b
it ch
anne
l x 6
4-by
te b
urst
32-b
it ch
anne
l x 1
28-b
yte
burs
t
8-bi
t cha
nnel
x 3
2-by
te b
urst
16-b
it ch
anne
l x 1
28-b
yte
burs
t8-
bit c
hann
el x
64-
byte
bur
st
8-bi
t cha
nnel
x 1
28-b
yte
burs
t
OP
TIM
AL
BU
RS
T W
IDT
HS
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
this
is li
ke s
ayin
g
i hav
e 4
800M
Hz
8-bi
t Ram
bus
chan
nels
... w
hat s
houl
d i d
o?
- ga
ng th
em to
geth
er?
- ke
ep th
em in
depe
nden
t?
- so
met
hing
in b
etw
een?
like
befo
re, w
e se
e th
at m
ore
bank
s is
bet
ter,
but n
ot a
lway
s by
muc
h
Fo
cus
on
3.2
GB
/s —
MC
F
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
Cycles per Instruction (CPI)
01234567
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
with
larg
e bu
rsts
, the
re is
less
in
terle
avin
g of
requ
ests
, so
extr
a ba
nks
are
not n
eede
d
Fo
cus
on
3.2
GB
/s —
MC
F
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
Cycles per Instruction (CPI)
01234567
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
#Ban
ks n
ot
par
ticu
larl
y im
po
rtan
tg
iven
larg
e b
urs
t si
zes
...
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
with
mul
tiple
inde
pend
ent
chan
nels
, you
hav
e a
degr
ee o
f co
ncur
renc
y th
at, t
o so
me
exte
nt, O
BV
IAT
ES
TH
E N
EE
D
for
BA
NK
ING
Fo
cus
on
3.2
GB
/s —
MC
F
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
Cycles per Instruction (CPI)
01234567
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
... e
ven
less
so
w
ith
mu
lti-
chan
nel
sys
tem
s
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
how
ever
, try
ing
to r
educ
e ex
ecut
ion
time
via
mul
tiple
ch
anne
ls is
a b
it ris
ky:
it is
ver
y S
EN
SIT
IVE
to B
UR
ST
S
IZE
, bec
aus
emul
tiple
ch
anne
ls g
ivee
s th
e lo
nges
t la
tenc
y po
ssib
le to
EV
ER
Y
RE
QU
ES
T in
the
syst
em, a
nd
havi
ng L
ON
G B
UR
ST
S
exac
erba
tes
that
pro
blem
--
byt
incr
easi
ng th
e le
ngth
of t
ime
that
a
requ
est c
an b
e de
laye
d by
w
aitin
g fo
r an
othe
r ah
ead
of it
in
the
queu
e
Fo
cus
on
3.2
GB
/s —
MC
F
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
Cycles per Instruction (CPI)
01234567
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
Mu
lti-
chan
nel
sys
tem
s so
met
imes
(bu
t n
ot
alw
ays)
a g
oo
d id
ea
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
anot
her
way
to lo
ok a
t it:
how
doe
s th
e ch
oice
of b
urst
si
ze a
ffect
the
NU
MB
ER
or
WID
TH
of c
hann
els?
=>
WID
E C
HA
NN
ELS
: an
impr
ovem
ent i
s se
en b
y in
crea
sing
the
burs
t siz
e
=>
NA
RR
OW
CH
AN
NE
LS:
eith
er n
o im
prov
emen
t is
seen
, or
a s
light
deg
rada
tion
is s
een
by in
crea
sing
bur
st s
ize
Fo
cus
on
3.2
GB
/s —
MC
F
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
Cycles per Instruction (CPI)
01234567
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
4x 1
-byt
e ch
ann
els
2x 2
-byt
e ch
ann
els
1x 4
-byt
e ch
ann
els
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
we
see
the
sam
e tr
ends
in a
ll th
e be
nchm
arks
sur
veye
d
the
onlll
y th
ing
that
cha
nges
is
som
e of
the
rela
tions
bet
wee
n pa
ram
eter
s ...
Fo
cus
on
3.2
GB
/s —
BZ
IP
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
Cycles per Instruction (CPI)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
012
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
for
exam
ple,
in B
ZIP
, the
bes
t co
nfigu
ratio
ns a
re a
t sm
alle
r bu
rst s
izes
than
MC
F
how
ever
, tho
ugh
TH
E O
PT
IMA
L C
ON
FIG
cha
nges
from
ba
nchm
ark
to b
ench
mar
k, th
ere
are
alw
ays
seve
ral c
onfig
s th
at
are
with
in 5
-10%
of t
he o
ptim
al
confi
g --
IN A
LL B
EN
CH
MA
RK
S
Fo
cus
on
3.2
GB
/s —
BZ
IP
3.2
GB
/s S
yste
m B
andw
idth
(ch
anne
ls x
wid
th x
spe
ed)
Cycles per Instruction (CPI)
32-B
yte
Bur
st64
-Byt
e B
urst
128-
Byt
e B
urst
012
1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes 4 ch
an x
1 b
yte 1 ch
an x
4 b
ytes
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte 1
chan
x 4
byt
es
2 ch
an x
2 b
ytes
4 ch
an x
1 b
yte
8 B
anks
per
Ch
ann
el4
Ban
ks p
er C
han
nel
2 B
anks
per
Ch
ann
el1
Ban
k p
er C
han
nel
BE
ST
CO
NF
IGS
are
at
SM
AL
LE
R B
UR
ST
SIZ
ES
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Qu
eue
Siz
e &
Reo
rder
ing
0123
BZ
IP:
1.6
GB
/s (
1 ch
ann
el)
32-b
yte
burs
t64
-byt
e bu
rst
128-
byte
bur
st
Cycles per Instruction (CPI) 1 bank/channel
2 banks/ch
annel
4 banks/ch
annel
8 banks/ch
annel 1 bank/channel
2 banks/ch
annel
4 banks/ch
annel
8 banks/ch
annel1 bank/c
hannel
2 banks/ch
annel
4 banks/ch
annel
8 banks/ch
annel
32-E
ntr
y Q
ueu
eIn
fin
ite
Qu
eue
1-E
ntr
y Q
ueu
eN
o Q
ueu
e
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
we
have
a c
ompl
ex e
dsig
n sp
ace
whe
re n
eigh
borin
g de
sign
s di
ffer
sign
ifica
ntly
if yo
u ar
e ca
refu
l, yo
u ca
n be
at
the
perf
orm
ance
of t
he a
vera
ge
orga
niza
tion
by 3
0-40
%
supp
ortin
g m
emor
y co
ncur
renc
y im
prov
es s
yste
m p
erfo
rman
ce,
as lo
ng a
s it
is n
ot d
one
at th
e ex
pens
e of
mem
ory
late
ncy:
- us
ing
MU
LTIP
LE C
HA
NN
ELS
is
goo
d, b
ut n
ot b
est s
olut
ion
- m
ultip
le b
anks
/cha
nnel
is
alw
ays
good
idea
- try
ing
to in
terle
ave
smal
l bur
sts
is in
tuiti
vely
app
ealin
g, b
ut it
do
esn’
t wor
k-
MS
HR
s: a
lwas
a g
od id
ea
In g
ener
al, b
urst
s sh
ould
be
larg
e en
ough
to a
mor
tize
the
prec
harg
e co
st.
Dire
ct R
ambu
s =
16
byte
sD
DR
2 =
16/
32 b
ytes
TH
IS IS
NO
T E
NO
UG
H
Co
ncl
usi
on
s
DE
SIG
N S
PAC
E is
NO
N-L
INE
AR
,C
OS
T o
f M
ISJU
DG
ING
is H
IGH
CA
RE
FU
L T
UN
ING
YIE
LD
S 3
0–40
% G
AIN
MO
RE
CO
NC
UR
RE
NC
Y =
= B
ET
TE
R(b
ut
no
t at
exp
ense
of
LA
TE
NC
Y)
•V
ia C
han
nel
s→
NO
T w
/ LA
RG
E B
UR
ST
S•
Via
Ban
ks→
ALW
AY
S S
AF
E•
Via
Bu
rsts
→ D
OE
SN
’T P
AY
OF
F•
Via
MS
HR
s→
NE
CE
SS
AR
Y
BU
RS
TS
AM
OR
TIZ
E C
OS
T O
F P
RE
CH
AR
GE
•Ty
pic
al S
yste
ms:
32
byte
s (e
ven
DD
R2)
→ T
HIS
IS N
OT
EN
OU
GH
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Ou
tlin
e
•B
asic
s
•D
RA
M E
volu
tio
n: S
tru
ctu
ral P
ath
•A
dva
nce
d B
asic
s
•D
RA
M E
volu
tio
n: I
nte
rfac
e P
ath
•F
utu
re In
terf
ace
Tren
ds
& R
esea
rch
Are
as
•P
erfo
rman
ce M
od
elin
g:
Arc
hit
ectu
res,
Sys
tem
s, E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Em
bed
ded
DR
AM
Pri
mer
DR
AM
Arr
ay
CP
UC
ore
CP
UC
ore
DR
AM
Arr
ay
Em
bed
ded
No
t E
mb
edd
ed
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Wh
ith
er E
mb
edd
ed D
RA
M?
Mic
rop
roce
sso
r R
epo
rt, A
ug
ust
199
6: “
[Fiv
e]A
rch
itec
ts L
oo
k to
Pro
cess
ors
of
Fu
ture
”
•Tw
o p
red
ict
imm
inen
t m
erg
er
of
CP
U a
nd
DR
AM
•A
no
ther
sta
tes
we
can
no
t ke
ep c
ram
min
g
mo
re d
ata
over
th
e p
ins
at f
aste
r ra
tes
(im
plic
atio
n: e
mb
edd
ed D
RA
M)
•A
fou
rth
wan
ts g
igan
tic
on
-ch
ip L
3 ca
che
(per
hap
s D
RA
M L
3 im
ple
men
tati
on
?)
SO
WH
AT
HA
PP
EN
ED
?
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
Em
bed
ded
DR
AM
for
DS
Ps
MO
TIV
AT
ION
DS
P C
om
pile
rs =
> Tr
ansp
aren
t C
ach
e M
od
el
NO
N-T
RA
NS
PAR
EN
T a
ddre
ssin
gE
XP
LIC
ITLY
MA
NA
GE
D c
onte
nts
TR
AN
SPA
RE
NT
add
ress
ing
TR
AN
SPA
RE
NT
LY M
AN
AG
ED
con
tent
s
TAG
LE
SS
SR
AM
TR
AD
ITIO
NA
L C
AC
HE
(har
dwar
e-m
anag
ed)
CA
CH
E
MA
INM
EM
OR
Y
Mov
e fr
omm
emor
y sp
ace
to “
cach
e” s
pace
crea
tes
a ne
w,
equi
vale
nt d
ata
obje
ct, n
ot a
mer
e co
py o
f th
e or
igin
al.
Add
ress
spa
cein
clud
es b
oth
“cac
he” a
nd
prim
ary
mem
ory
(and
mem
ory-
map
ped
I/O)
MA
INM
EM
OR
Y
Add
ress
spa
cein
clud
es o
nly
prim
ary
mem
ory
(and
mem
ory-
map
ped
I/O)
The
cac
he “
cove
rs”
the
entir
e ad
dres
ssp
ace:
any
dat
umin
the
spac
e m
ay b
eca
ched
CA
CH
E
Cop
ying
from
mem
ory
to c
ache
cre
ates
asu
bord
inat
e co
py o
fth
e da
tum
that
is
kept
con
sist
ent w
ithth
e da
tum
stil
l in
mem
ory.
Har
dwar
een
sure
s co
nsis
tenc
y.
HA
RD
WA
RE
man
ages
th
ism
ovem
ent
of
dat
a
SO
FT
WA
RE
man
ages
th
ism
ovem
ent
of
dat
a
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
DS
P B
uff
er O
rgan
izat
ion
Use
d fo
r S
tud
y
Ban
dw
idth
vs.
Die
-Are
a Tr
ade-
Off
for
DS
P P
erfo
rman
ce
DS
P
S0
S1
DS
P
Fu
lly A
sso
c 4-
Blo
ck C
ach
e
Ld
St0
Ld
St1
Ld
St0
Ld
St1
buff
er-0
buff
er-1
vict
im-0
vict
im-1
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
E-D
RA
M P
erfo
rman
ce
0.4
GB
/s
0.8
GB
/s
1.6
GB
/s
3.2
GB
/s
6.4
GB
/s
12.8
GB
/s
25.6
GB
/s
Ban
dwid
th
CPI Em
bedd
ed N
etw
orki
ng B
ench
mar
k -
Patr
icia
200M
Hz
C60
00 D
SP :
50,
100
, 200
MH
z M
emor
y
#
#
##
#
#
##
##
#
#
##
#
024681032
byt
es
64 b
ytes
128
byte
s
256
byte
s
512
byte
s#
#
1024
byt
es
Cac
he L
ine
Siz
e
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
E-D
RA
M P
erfo
rman
ce
0.4
GB
/s
0.8
GB
/s
1.6
GB
/s
3.2
GB
/s
6.4
GB
/s
12.8
GB
/s
25.6
GB
/s
Ban
dwid
th
CPI Em
bedd
ed N
etw
orki
ng B
ench
mar
k -
Patr
icia
200M
Hz
C60
00 D
SP :
50M
Hz
Mem
ory
#
#
##
#
#
##
##
#
#
##
#
0246810
Incr
easi
ng b
us w
idth
32 b
ytes
64 b
ytes
128
byte
s
256
byte
s
512
byte
s#
#
1024
byt
es
Cac
he L
ine
Siz
e
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
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RA
M P
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rman
ce
Ban
dwid
th
CPI Em
bedd
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etw
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ng B
ench
mar
k -
Patr
icia
200M
Hz
C60
00 D
SP :
100
MH
z M
emor
y
#
##
##
#
#
##
#
#
#
##
#
0246810
0.4
GB
/s
0.8
GB
/s
1.6
GB
/s
3.2
GB
/s
6.4
GB
/s
12.8
GB
/s
25.6
GB
/s
Incr
easi
ng b
us w
idth
32 b
ytes
64 b
ytes
128
byte
s
256
byte
s
512
byte
s#
#
1024
byt
es
Cac
he L
ine
Siz
e
DR
AM
TU
TOR
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ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
NO
TE
E-D
RA
M P
erfo
rman
ce
#
#
##
#
#
#
##
##
##
##
0.4
GB
/s
0.8
GB
/s
1.6
GB
/s
3.2
GB
/s
6.4
GB
/s
12.8
GB
/s
25.6
GB
/s
Ban
dwid
th
0246810 CPI Em
bedd
ed N
etw
orki
ng B
ench
mar
k -
Patr
icia
200M
Hz
C60
00 D
SP:
200M
Hz
Mem
ory
Incr
easi
ng b
us w
idth
32 b
ytes
64 b
ytes
128
byte
s
256
byte
s
512
byte
s#
#
1024
byt
es
Cac
he L
ine
Siz
e
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Per
form
ance
-Dat
a S
ou
rces
“A P
erfo
rman
ce S
tudy
of C
onte
mpo
rary
DR
AM
Arc
hite
ctur
es,”
Pro
c. IS
CA
’99.
V. C
uppu
, B. J
acob
, B. D
avis
, and
T. M
udge
.
“Org
aniz
atio
nal D
esig
n Tr
ade-
Offs
at t
he D
RA
M, M
emor
y B
us, a
nd
Mem
ory
Con
trol
ler
Leve
l: In
itial
Res
ults
,” U
nive
rsity
of M
aryl
and
Tech
nica
l Rep
ort U
MD
-SC
A-T
R-1
999-
2. V
. Cup
pu a
nd B
. Jac
ob.
“DD
R2
and
Low
Lat
ency
Var
iant
s,” M
emor
y W
all W
orks
hop
2000
, in
conj
unct
ion
w/ I
SC
A ’0
0. B
. Dav
is, T
. Mud
ge, V
. Cup
pu, a
nd B
. Jac
ob.
“Con
curr
ency
, Lat
ency
, or
Sys
tem
Ove
rhea
d: W
hich
Has
the
Larg
est
Impa
ct o
n D
RA
M-S
yste
m P
erfo
rman
ce?”
P
roc.
ISC
A ’0
1. V
. Cup
pu a
nd B
. Jac
ob.
“Tra
nspa
rent
Dat
a-M
emor
y O
rgan
izat
ions
for
Dig
ital S
igna
l Pro
cess
ors,
” P
roc.
CA
SE
S ’0
1. S
. Srin
ivas
an, V
. Cup
pu, a
nd B
. Jac
ob.
“Hig
h P
erfo
rman
ce D
RA
Ms
in W
orks
tatio
n E
nviro
nmen
ts,”
IEE
E T
rans
actio
ns o
n C
ompu
ters
, Nov
embe
r 20
01.
V. C
uppu
, B. J
acob
, B. D
avis
, and
T. M
udge
.
Rec
ent e
xper
imen
ts b
y S
adag
opan
Srin
ivas
an, P
h.D
. stu
dent
at
Uni
vers
ity o
f Mar
ylan
d.
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
Ack
no
wle
dg
men
ts
Th
e p
rece
din
g w
ork
was
su
pp
ort
ed
in p
art
by t
he
follo
win
g s
ou
rces
:
•N
SF
CA
RE
ER
Aw
ard
CC
R-9
9836
18
•N
SF
gra
nt
EIA
-980
6645
•N
SF
gra
nt
EIA
-000
0439
•D
OD
aw
ard
AF
OS
R-F
4962
0011
0374
•…
an
d b
y C
om
paq
an
d IB
M.
DR
AM
TU
TOR
IAL
ISC
A 2
002
Bru
ce J
acob
Dav
id W
ang
Uni
vers
ity o
fM
aryl
and
CO
NTA
CT
INF
O
Bru
ce J
aco
b
Ele
ctri
cal &
Co
mp
ute
r E
ng
inee
rin
gU
niv
ersi
ty o
f M
aryl
and
, Co
lleg
e P
ark
http://www.ece.umd.edu/~blj/
Dav
e W
ang
Ele
ctri
cal &
Co
mp
ute
r E
ng
inee
rin
gU
niv
ersi
ty o
f M
aryl
and
, Co
lleg
e P
ark
http://www.wam.umd.edu/~davewang/
UN
IVE
RS
ITY
OF
MA
RY
LAN
D