Post on 04-Jun-2018
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X86 - ISA
The 80x86 Family
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Name Date Transistors
Clockspeed
Datawidth
8080 1974 6K 2MHz 8
8086 1978 29K 5MHz 1680286 1982 134K 12 MHz 1680386 1985 275K 16-33 MHz 3280486 1989 1.2 M 20 -100
MHz
32
Pentium 1993 3.1M 60-200MHz
32 /64
PentiumII
1997 7.5 M 233-450MHz
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PentiumIII
1999 9.5M 450 -933MHz
32 /64
Pentium 4 2000 42 M 1.5 GHz 32/ 64
The Evolution of Microprocessors
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The 16-bit Processors
8086 20 Address lines 220 1 MB 2.5 MIPS
80286 24 Address lines 224 16 MB 4 MIPS
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The 32-bit Processors
80386 32 Address lines 232 4GB
80486 32 Address lines 232 4GB Floating Pt Unit Internal Cache 50 MIPS
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Characteristics of the X86 Family
CISC Instructions broken up into ops
Complex Instruction Decoder
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ESCSSSDSIP
1
2
3
4
5
6
Control & Timing
Memory Interface
ALU
OperandsFlags
EU
BIU
InstructionQueue
Block Diagram of 8086
AH AL
BH BL
CH CL
DH DL
BP
SP
SI
DI
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8086DataBus
Controlsignals
AddBus
A0A19
D0D15
8086 - Buses
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A19A00.0 00000 H
1.1 FFFFFH
MemoryAddressSpace
00000 H
FFFFFH
Memory Address Space
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Fetches Instruction
Executes Instruction
BIU
EU
Microprocessor
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BIU
ALU
Control& Timing
EU
Address bus
RAMROM I/oPorts
Discs
Video
Data Bus
CLK
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Variation of 8086 - 8088
External Data Bus 8-bits Inst Queue 4 bytes
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X86 - ISA
8086-80486 Programmers Model
BIU
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Programmers Model - BIU
EIP IP
CS
DS
ES
SS
FS
GS
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IP = 3000 H
CS = 2000 H Base address
Offset address
Physical address
= 20000 H +3000 H
23000 H
2000 H : 3000 H
CS
DSES
SS
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CodeSegment
2000 0000
FFFF
3000
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Data
Code
Stack
Extra
4900 ES
3400 SS
1000 DS
2000 CS
00000 H
10000 H
20000 H1FFFFH
2FFFFH34000 H
43FFF H49000 H
58FFF H
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High Memory
HIMEM.SYS A20
Segment Address FFFFH Offset Address 4000 H 103FF0 H 03FF0 H
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X86 - ISA
8086-80486 Programmers ModelEU
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AX
BXCXDXSPBP
SIDI
Count
DataStack Pointer
Base Pointer
Source Index
Destination Index
Accumulator
Base Index
Programmers Model
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MULTIPURPOSE REGISTERS
AX, BX, CX, DX, BP, DI, SI
SPECIAL PURPOSE REGISTERS
IP, SP, FLAGS
CS, DS, SS, ES( Segment Registers )
Registers
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AX AH(8 bit)
AL(8 bit)
BX BH BL
CX CH CL
DX DH DL
(Accumulator)
(Base Register)
(Used as a counter)
(Used to point to data in I/O operations)
Registers - MPR
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Programmers Model -MPR
EAX AH AL
EBX BH BL
ECX CH CL
EDX DH DL
EBP BP
ESI SI
EDI DI
ESP SP
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Default 16 bit segment and offset addresscombinations
Segment offset special purpose
CS
SS
DS
ES
IP
SP (or) BP
BX,DI,SIan 8-bit number
16
bit numberDI for stringInstructions
InstructionAddress
Stack address
Data address
String destinationaddress
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Flags
Status Control
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Flag Register
AC
VM
RF
NT
O D I T S Z A P CIOPL
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