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1

()

/

Algorithm

:Two passesAlgorithm

PASS 1:

diagram- Pass 1)4.1(:

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2

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(12)

(11)

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3

MACRO CALLS and EXPANSION

)Macro Expansion(

MACRO CALL

bodyMDT.

PASS 2:

diagram Pass 2)4.1(:

-source card)Pass 1.(

-MNToperation code.

-MACRO.

- (MDTIndex

MDT Index MNT(Index

MDT)(MDTP.

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4

Index Name MDT Index

.

.

.

3

.

.

.

.

.

.

INCR

.

.

.

.

.

.

15

.

.

.

(MNT)

Index Card

.

1516

17

18

19

.

.

..

MACRO BODY.

.

.

(MDT) )(

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5

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)(10)

(11)

(12)

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6

: Macro Processor

Macro

source program

source program Assembler

object program:

-object programvalues

()RAMaddresses

.

-three operationsobject program:

-Loading.

-Relocation, or Movement.

-Linking.

:object program.

Sourceprogram

MacroProcessor

Source

program

After

Macro

Expansion

Assembler Objectprogram

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7

:object programaddress.

:

:

Loader

))LoadingObject program

.

Object program Memory

Address 0

Move to

Object program Memory at specified address

Move to

(a)

(b)

Program 1

(c)

Program 2 Program n

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8

Loaders Types

:

Absolute LoadersDirect-Linking Loaders.

:Loader

:-

-Allocation:

.

address 0000

address

2100 bytes)a(:

)(

.

.

A

.

.

A

.

.

.

.

.

0000

21003000

5100A

(a) (b)

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9

-)Relocation:(.

address 3000

5100

)b.(

address

2100

:

Assembler Loader

3000

.

-Linking:. A, B

:

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)(

-Loading:.

- :object program

.

-

.

(B)

Loader

Databases

(A)

(A)

(B)

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))Absolute Loader

.

:

)(

Assembler

:.

Loader

Object

Program 1Object

programsready for

execution

Loader

Object

Program 2

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- Assembler address

.

- subroutines

address addresslinksubroutine.