assembly midterm exam

8/13/2019 Assembly Midterm exam

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uestion 1 :study the following program and determine contents of the registers listed in the pagebelow

after executing the following program :

.Model tiny

. code

. starup

MOV AX, 5000h

MOV ES, AX

MOV AX, 6000h

MOV BX, 7000h

MOV CX, 8000h

MOV DX, 9000h

MOV DI, 0700h

MOV BP, 0800h

MOV SI, 0002h

MOV SP, 6000h

PUSH AX

PUSH BX

PUSH DX

POP DX

PUSH SI

PUSH SX

PUSH BP

PUSH SP

POP DI

PUSH DI


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POP SI

POP BX

POP AX

POP BP

.exit

END

What is the values of DI,BP,AX,DX and SP ?!

Question 2 :

Imagine we consrust an assembly program that consists of three assembly instructions to

perform a certain job . the corresponding logical addressassociated with each instruction as

shown below :

0018:0020 Assembly Instruction 1

0018:0023 Assembly Instruction 2

0018:0026 Assembly Instruction 3; three bytes long

Answer the following qwestions :

(a) At which memory segment the above intsructions are stored ?

(b) What are the physical addresses generated to fetch instruction 2 considering real

mode memory addresses ?

(c) What are the physical addresses gencrated to fetch instruction 3 considering

protected mode memory addressing ? ( Consider an 80286prcessor that has 24-bit get

further benefit from Appendix D .


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Figure 1. part of global and local descriptor tables where all of the mentioned values are inhex

Question 3 :Classify the following instructions according to their addressing modes?

1) MOV CX,[1000H]2) MOV CX,[BX+SI+6000H]3) MOV [BX],AX4) MOV AL,[EBX+4*ECX]

Question 4 :state whether each of following is valid or invalid in addition the major cause for that :

1) MOV SS,DS

Local Descriptor Table (L O T)

Descriptor 1

L O T: Descriptor 2 L O T : Descriptor 3

00 00 00

00 00 00

FE FA FF

10 10 20

00 40 10

00 30 10

FF FF 00

FF FF FF

Global descriptor Table (G D T):

Descriptor1

G D T: Descriptor 2 G D T: Descriptor 2

00 00 00

00 00 00

9F 9A 9E

10 10 40

00 10 10

00 00 10

11 22 66

FF FF FF


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teishat

2) MOV DX,CH3) MOV [BX],1234H4) MOV DX,[AX]5) MOV BH,[EBX+5*ECX]6) MOV CS,DX7) MOV CH,[XP+8000H]

Question 5 :the following table shows the logical memory addresses along with their contents. You need

to consider this table for answering questions below .

(a) What will be the value of BX after exccuting following code ?MOV AX, 0C000h

MOV DS, AX

MOV BH, 30H

MOV BI, 70H

(b) What will be the contents of CX and DX after exccuting the following code ?MOV CH, [000Dh]

MOV CL, [0006h]

MOV DX, [0005H]

(c ) What will be the contents of BP after executing the following code ?

MOV SI,[000AH]

MOV BX,[000EH]

MOV BP,[BX+SI]

Question 6 :Study the following Assembly program named Mid carefully , given that the starting offset

address of the data segment DS is 0009H

.Model small

.data

X DW 0004H

Y DW 558CH

Z DW 4FFCH

K DW 0FFCBH

.code


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.startup

MOV DI,OFFSET X

MOV BX,X

MOV DX,[BX+DI-2]

MOV CX,Y[BX-2]

.exit

END

Write down the value of registers DI,BX,DX and CX after executing this code above.

Question 7 :

The following variables are declared in the data segment , where DS= 1000H and the starting

offset = 0020H

.DATA

DATA1 DW 11C2H

DATA2 DW 264CH

DATA3 DW 3FFCH

DATA4 DB 40 DUP(ODEH)

(a) What will be the content of DI register after executing the following instructions ?LEA DI,DATA1

(b) How does the follownig instruction affect the data segment (DS) ?MOV WORD PTR [DI+4],0FFFFH

QUESTION 8 :Find the equivalent assembly instructions for these machine instructions :

898D0070H

8CDAH


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assembly midterm exam

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