CBP 2005-6Comp 1017 Digital Technologies1 Let’s make a Computer … at least the CPU … Pentium 4...

CBP 2005-6 Comp 1017 Digital Technologies 1

Let’s make a Computer

… at least the CPU …

Pentium 4

Pentium 3

Opteron

Ultra Sparc 1

21364Itanium 2 McKinley


CPU

Memory

Keyboard

VDU

Computer Program (Code)

1 do this

2 do that

3 now this

4 goto 1


Program Memory

2. High Level Language like ‘C’

3. Assembler Instructions

mov ax,[x]

mov bx,[y]

add ax, bx

mov [w],ax

w = x + y ;

1. Application

Let’s consider a spreadsheet cell which

adds two numbers x + y. This cell and its instruction

is in memory. But it is REPRESENTED in

different ways

Inside the CPU


Pentium

Data Cache Code Cache

Instruction Fetch

Instruction Decode

Execution Unit


Minimalist CPU

What do we need to build a CPU?

“Execution Unit”ALU (Arithmetic Logic Unit)

Memory (to store intermediate data)

Input Output

A good Name


Arithmetic Logic Unit

Input A Input B

Output

ALU

Integer Execution Unit

5

3 2

add 1

3 2

sub


Input A Input B

Output

ALU

ALU

MMX instructions add bits of images together! Useful for multimedia

Multimedia MMX


5

3 2

add

0

1

2

3

4

3

2

5

Processing Idea Nr. 1

Move data from memory

Move data into memory3.

2.

1.

Memory DRAM, Hard Disk ..

Move data in and out of data memory store


5

3 2

add

0

1

2

3

4

3

2

5

Processing Idea Nr.2

IP

(Code Memory)

mov 3 in from memory

mov 2 in from memory

add the two numbers

mov the result to memory

Instruction Memory

Program

Move instructions into CPU from code memory


Registers

0

1

4

6 8

6

8

4

Registers are high-speed memory on the CPU chip

Parking places for data on the move

AX and BX are used for ALU operations

MAR is memory address register, here 4. So result, 6+8=14 will go into memory cell address 4

AX BX

MAR


ip

Data Memory

Instruction

Memory

0

1

4

mar

Our computer so far …


Instruction

Memory

A couple of extra bits

Data Memory

0

1

4

Instruction Register

Memory Data Register 2

8

34

34

2

Data

Address

add ax,bx

1. Line of code goes in

2. Electrical bit signals come out

2.

1.

• Energize ax• Energize bx• Select ALU “add"


SAM-2


Moving data into Registers

Instruction

Memory

0

1

2

mar 3

4

mov ax , [1]

85

8

7

6

1

BXAXmov ax , [1] mov bx , [2]mov bx , [2] 7

For example …


Moving data into Memory

Instruction

Memory

0

1

2

mar 3

4

mov [3] , ax

85

8

7

6

1

BXAXmov [3] , axmov [0], bx

mov [0] , bx 7

For example …

8

7


Adding Numbers

Instruction

Memory

0

1

2

mar 3

4

add ax , bx

85

7

6

1

BXAXAdd ax,bx

7

For example …

… this means ‘ add ax to bx,

put the answer in ax’8

8 7

15


I’ve never wrestled with

such a complex

problem before

It must take a lot of organization and control !


Pentium

Organization and

control


Fetch-Execute Cycle

1. Fetch instruction from memory

2. Decode the instruction and read any

registers

3. Do any ALU operations (execute units)

5. Write back results to registers

(Organization and Control)

add ax , bx

4. Do any Memory Access

ALU <- ax ALU <- bx

ax + bx

(Data cache)

ax <- ALU

None needed


add ax , bx

add ax,bx

add ax

0

1

4

3

2

bx

Fetch-Exec : State 1Instruction Fetch

8

3

7

1

9

3 1

AX BX


0

1

4

3

2

Fetch-Exec : State 2Decode, Register Operations

8

3

7

1

9

add ax , bx

add ax,bx

add ax bx

3 1

3 1

AX BX


0

1

4

3

2

Fetch-Exec : State 3ALU Operation

8

3

7

1

9

add ax , bx

add ax,bx

add ax bx

AX BX

3 1

4


0

1

4

3

2

Fetch-Exec : State 4Memory Access

8

3

7

1

9

add ax , bx

add ax,bx

add ax bx

AX BX

3 1

4


0

1

4

3

2

Fetch-Exec : State 5Register Write

8

3

7

1

9

add ax , bx

add ax,bx

add ax bx

BX

3 1

4

4


Fetch-Execute Cycle

1. Fetch instruction from memory

2. Decode the instruction and read any

registers

3. Do any ALU operations (execute units)

5. Write back results to registers

(Organization and Control)

mov ax , [1]

4. Do any Memory Access

Read the ‘1’

Put ‘1’ into MAR

Data into ax

Read memory at addr ‘1’


mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 1Instruction Fetch

8

3

7

1

9


mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 2Decode, Register Operations

8

3

7

1

9


mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 3ALU Operation

1

8

3

7

1

9


mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 4Memory Access

1

8

3

7

1

9

8


mov ax , [1]

mov ax , [1]mov ax

0

1

4

3

2

1

Fetch-Exec : State 5Register Write

1

8

3

7

1

9

88


Pentium

5

1

2

3

4

1. Fetch

2. Decode

3. ALU

4. Mem Ops

5. Reg Write


The first microprocessor

KeypadLots of

ElectronicsLCD Display

Keypad LCD Display

Code Memory

Programmable Electronics

A dedicated design ...

... or a re- usable design

CBP 2005-6Comp 1017 Digital Technologies1 Let’s make a Computer … at least the CPU … Pentium 4...

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