Computer Architecture Chapt 9-2

8/11/2019 Computer Architecture Chapt 9-2

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Chap. 9 Instruction Set Architecture



Data Transfer Instructions

Memory Memory

: move, exchange

Registers Memory

: load, store, exchange

Registers Registers

: move, exchange




Stack instructions

– Memory stacks:

• A portion of a memory address space.

• Store state info. related to procedure calls/returns and

interrupts

- PUSH

SP SP – 1

M[SP]

R1

- POP

R1 M[SP]

SP SP +1




I/O instructions

– Ports• Registers with I/O lines attached to I/O

devices – How to port addresses are assigned

• Independent I/O systems – Separate address field for addressing ports

• Memory-mapped I/O – No separate memory locations in one common

address range

– No distinct I/O instructions



Data Manipulation Instructions

Arithmetic Instruction

Logical and bit manipulation instructions

Shift instructions



Arithmetic Instructions

111…1 000…0

000…0 111…1

2’s complement



Logical and Bit Manipulation Instructions

Mask instruction

X · 0 = 0

Bit complement

X 1 = X’





Program Control Instructions

CMP R5, R6, TO1...

TO1:

Comparison via a subtraction

Set or reset status bits

Comparison via a AND

Set or reset status bits

CMP R5, R6, R1

TEST R5, R6, R1

(Examples)




CMP R5, R6

BZ TO1

.

.

.

TO1:




CMP R5, R6

BHE TO1

.

.

.

TO1:




CMP R5, R6

BGE TO1

.

.

.

TO1:




Procedure Call and Return Instructions

호출함수 피호출함수

int main(void){

… …

puts(“Hi, Mom!”);

… … }

Code for puts()… … … …

…




main함수

...

함수 A 를 호출

...

함수 A Main함

함 A

호출

Stack조에

의해

현

SP




CALL B10

.

.

.

;---------------------------------------

B10 PROC

CALL C10

…

RET

B10 ENDP

;---------------------------------------

C10 PROC

…

RET

C10 ENDP

;---------------------------------------

SP SP-1

M[SP] PC

PC effective address

PC M[SP]

SP SP+1



Program Interrupt

Program interrupt

– transfer control from a program that is currently running toanother service program as a result of an externally orinternally request

– Handling a variety of situations that requre a departure from

the normal program sequence

Service program

User program{

… …

… …

}

… …

… … …



Program Interrupt

External Interrupts

– Come from I/O device, timing devices, circuit monitoringpower supply, or any other external source

• I/O requests, I/O completion

• Time-out interrupt

• Power failure interrupt

Internal Interrupts (traps)

– Come from illegal or erroneous use of an instruction or data

• Arithmetic overflow

• Divide-by-zero

• Memory stack overflow

• Protection violation

Software Interrupts

– A special instruction that behaves like an interrupt, used byprogrammer

• System call instruction: Ex) user I/O requests

•

User mode System (OS) mode



Processing Internal Interrupts

Instructions related to EI

- ENI: enable interrupt

- DSI: disable interrupt

Microinstructions for interrupt

SP SP-1

M[SP] PC ; return addr.

SP SP-1

M[SP] PSR

EI 0

INTACK 1

PC IVAD ; interrupt vector addr.

…



Floating-point Computations

Representation: (fraction, exponent)

– F 2E = +(0.1001110)2 2+4

Range of numbers – In case of computer with 48-bit registers

• Integer: (247-1)

• Floating-point number: (1-2-35)

2+(2048-1)

– Sign: 1bit, Fraction: 35bits, Exponent: 12bits




Arithmetic operations

.5372400 x 102

+ .1580000 x 10-1

.5372400 x 102

+ .0001580 x 102

.5373980 x 102

.56780 x 105

+ .56430 x 105

.00350 x 105

.35000 x 103

.5372400 x 102

x .1580000 x 10-1




Biased Exponent

– Bias: an excess number added to the exponent so that

all exponents become positive

– Advantages

• Only positive exponents

• Simpler to compare the relative magnitude




Standard Operand Format of floating-point

numbers

– Single-precision data type: 32bits

• ADDFS

– Double-precision data type: 64bits

• ADDFL




Significand

– A leading bit to the left of the implied binary point,

together with the fraction in the field

f field Significand Decimal Equivalent100…0 1.100…0 1.50

010…0 1.010…0 1.25

000…0 1.000…0 1.00

).1(2)1( 1272 f e

)211(2 23127

)0.1(2 126

~)211(2 23127

~




e=255 (11111111), f=0 + , -

e=255 (11111111), f

0 NaN (Not-a-Number) , Ex) 0 x = ?

e=0 (00000000) , f=0 +0, -0

e=0 (00000000) , f

0 < minimum value

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Computer Architecture Chapt 9-2

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