Assume that the offset is beginning at EF00H, what is the offset
of data that contain value (55)?
Marks DB 88, 44, 55, 90, 77 Answer: EF02H
Assume that the offset is beginning at EF00H, what is the offset
of data that contain value (55)?
Marks DW 88, 44, 55, 90, 77 Answer:EF04H
Assume that the offset is beginning at 2EF00H, what is the offset
of data that contain value (5)?
Std DD 1, 6, 5,8,9 Answer:2EF08H
What is the content of AX, after the execution of the following instructions?
MOV AL, 95
SUB AH, AH
MOV BH, 10
DIV BH
Answer: 0509H
Number of the times the instruction sequence below will loop before coming out of loop is
MOV AL, 00H
Al: INC AL
JNZ Al
Answer:256
After execution the following instructions, what is the contents of the register AX. Give your
answer in Hexadecimal.
array DW 1111H, 2222H, 3333H, 4444H
MOV BX, 1
MOV SI, 6
MOV AX, array[BX] [SI-2]
Answer:4433H
)‫ مختلف عليها ع الكىمبايلر‬4444)/ ‫عند الدكتىر‬4433
Write the contents of AX, CX, and Flags in this order (CF, PF, AF, SF, and ZF) after the
execution of the following instructions.
MOV CX, 0604H
MOV AX, OA98H
SHL AH, CL
ADD CX, AX
Answer: AX=0A80H,CX=1084H,CF=0,PF=0,AF=0,SF=1,ZF=0
Consider the following fragment of assembly code:
DATA
DW 7,6,5,4
COUNTER EQU 4
…
XOR AX, AX
STC
MOV CX, COUNTER
MOV SI, OFFSET DATA
NEW:
ADC AX, WORD PTR [SI]
ADD SI, 2
LOOP NEW
NEXT:
--------------What will be the value in AX when control reaches NEXT? Answer:23
Assume AL register contains the ASCII code for a letter Z; we need to convert to z. Write
one instruction to do that.
Answer:
MOV AL,Z
OR AL,00100000B ;20H
Assume the following same initial processor state
AX 6521H
CF
AF ZF
SF PF
BX ABCDH
1
0
1
0
0
CX 0105H
DX 876FH
OF
0
What are the flags after CMP AH, CL
Answer : CF=0,ZF=0,SF=0
Assume the following same initial processor state
AX 6521H
BX ABCDH
CF
AF ZF
SF
PF
CX 0105H
1
0
1
0
0
DX 876FH
What will be the contents of AX after SUB AL, AH ?
Answer: AX=65BCH
OF
0
Write a subroutine that makes all bits of the register Al zero if the least and most significant bit
of AL are 0, otherwise, makes all bits of AL one.
Answer:
MOV BL,AL
OR BL,01111110B
CMP BL,01111110B
JE ZERO
MOV AL,OFFH
RET
ZERO:
MOV AL,00H
RET
Consider the following Boolean expression:
IF ((X>Y)AND (Z < T))OR (A± B) THEN C = D
Write an assembly language code to implement the above expression. Assume that all variables are declared.
Answer:
COM
JA
CMP
MOV
JMP
OA:
CMP
JMP
MOV
Z,T
OA
X,Y
C,D
DONE
A,B
DONE
C,D
Write on line to declare 120 4-Bytes words, starting at memory location with offset 1200H, all initialized to 0,
and name it DATA .
Answer:
ORG 1200H
DATA QB 120 DUP(0)
We need to multiplies the most significant 4 bits and least significant 4 bits of register AX, write a subroutine to
do that.
Answer:
MOV
BL,AL
AND
AX,0F000H
MOV
CX,4H
MOV
AL,AH
ROR
AL,CL
AND BL,0FH
MUL
BL
RET
Write the contents of AX, and Flags in this order (CF, PF. AF, SF. And ZF) after the execution of the
following instructions
MOV
MUL
SUB
ADC
AX, 8F0AH
AL
AH, AL
AX, AX
Answer:AX=38C9H,CF=1,PF=1,AF=0,SF=0,ZF=0
Q1. (5%) According to the figure below that shows the memory circuit of 8086 microprocessor.
Note: A16 – A19 are not used, (don’t cares).
=
1. What is the total size of the memory in the circuit?
Answer:4k
2. What are the beginning and ending address of the memory in chip 1?
Answer:8800H-8FFFH
3. What are the beginning and ending address of the memory in chip 2?
Answer: B000H-B7FFH
4. Are the memory chips in circuit ROM or RAM? Why?
Answer: ROM , HAVE ONLY READ SIGNAL RD
5. How will you replace the two NANDs gates in the circuit with one 3-to-8 decoder without changing the
memory size or the memory addresses? Assume that the decoder has one active high enable G1, and two
active low enables G2A , G2B. Attach your sketch.
Y1 TO Chip 1,Y6 TO chip2
Q2 For an 8086 system working in real mode, the following address decoding circuit is given.
1. What range of addresses (in H) corresponds to each output of the decoders?
2. What is the total number of bytes in all ranges decoded by using this circuit?
SIZE OF MEMORY = 16 KBYTE
Q3 Design a memory interface for the 8086, which will provide 256K bytes of SRAM, organized as 128K
x 16 bits, starting at address 40000H and using SRAM chips 32K x 8 bit. The SRAM chips have three
control signals ̅̅̅̅̅, ̅̅̅̅ and ̅̅̅̅. Use the 74LS138 (3- to-8 decoder) for the implementation of the
decoding circuit. The 74LS138 has three control signals G1, ̅̅̅̅̅̅, and ̅̅̅̅̅̅.
‫بالدوسية الحمرا‬
Q4. There is a need to add 56K byte of memory to a certine microprocessor based system (20-bit address
bus and 8-bit data bus) in the address range A0000H – ADFFFH. The quantity of memory chips and the
corresponding address ranges are as follows:

4 (8Kx8) RAM chips will be used to decode A0000H – A7FFFH

2 (4Kx8) RAM chips will be used to decode A8000H – A9FFFH

1 (16Kx8) RAM chip will be used to decode AA000H – ADFFFH
a) Design an address decoding circuit using a 74LS139 decoder (search on how to use this decoder). Show
all connections and signals in detail.
b) Determine the available address range and size in KB in the memory map for any additional memory
chip.
Q1. Write an assembly language program to count how many times the character A is
repeated in a string entered by the user. Print the result on the screen taking into account
that the number of characters can be more than 9, but less than 255.
Assembly code:
table DB '0123456789ABCDEF'
RE DB 10,13 ,'NUMBER OF A IS : ','$'
.CODE
MOV BL,00H
MOV CX,10H
INPUT:
MOV AH,01
INT 21H
CMP AL,'A'
JNE CONT
INC BL
CONT:
LOOP INPUT
;NUMBER OF CHARS YOU WANT TO ENTER
MOV AH,09
MOV DX,OFFSET RE
INT 21H
;THE REST OF THE CODE I TOKE FROM THE INTERNET CAUSE WHEN I WAS
TRYING TO PRINT THE VALUE IN HEX IT CONVERTS IT INTO ASCII AND I DONT
KNOW HOW TO CONVERT IT, I HOPE IT DOESNT DO MUCH ON MY GRADE
MOV DL, BL
LEA BX, table ; load data table.
MOV AL, DL
SHR AL, 4 ; leave high part only.
XLAT ; get hex digit.
MOV AH, 0Eh ; teletype sub-function.
INT 10h
MOV AL, DL
AND AL, 0Fh ; leave low part only.
XLAT ; get hex digit.
MOV AH, 0Eh ; teletype sub-function.
INT 10h
HLT
ENDP
RET
Q2. Without using string advanced string operations, write an assembly program to check if a password
entered by the user is correct or not. Print “Your password is correct” or “You password is incorrect”
accordingly.
Code.
.model small
.DATA
PASSW DB 'ABCD1234'
TRUE DB 10,13, 'Your password is correct', '$'
FALSE DB 10,13, 'Your password is incorrect', '$'
.CODE
MOV SI,@DATA
MOV DS,SI
MOV DI,OFFSET PASSW
MOV CX,08H
INPUT:
MOV AH,01H
INT 21H
PUSH AX
PUSH [DI]
INC DI
LOOP INPUT
MOV CX,08H
CHECK:
POP AX
POP BX
CMP AL, BL
JNE NOTCORRECT
LOOP CHECK
MOV AH,09H
MOV DX, OFFSET TRUE
INT 21H
HLT
NOTCORRECT:
MOV AH,09H
MOV DX, OFFSET FALSE
INT 21H
HLT
ENDP
RET
1. ADD BX,[0220] is a legal operation.
Select one:
True
False
The correct answer is 'True.'
2. The total physical memory which can be interfaced to an 8086 processor is:
Select one:
a. 64 Kbyte
b. 64 byte
c. 1 Mbyte
d. 1 Gbyte
e. 1 Kbyte
The correct answer is: 1 Mbyte
3. The default segment size of an 8086 system is:
Select one:
a. 64 byte
b. 1 Gbyte
c. 64 Kbyte
d. 1 Kbyte
e. 1 Mbyte
The correct answer is: 64 Kbyte
4. Which of the following pins is used to enable the most significant bits of the data
bus during read/write operations?
Select one:
a. READY
b. BHE ’
c. RD’ & WR’
d. ALE
e. M/IO’
The correct answer is: 'BHE’
5. High level programming language is machine specific.
Select one:
True
False
The correct answer is 'False.'
6. MOV AX,DS is a legal operation.
Select one:
True
False
The correct answer is 'False.'
7. MOV CX,2255H is a legal operation.
Select one:
True
False
The correct answer is 'True.'
8. Which of the following pins is used in the demultiplexing of the 8086 Address/data
lines
Select one:
a. HOLD
b. DT/R’
c. BHE’
d. READY
e. ALE
The correct answer is: ALE
9. A0 -A19 are used to access address lines only.
Select one:
True
False
The correct answer is 'True.'
10.Which of the following pointers is used with the stack segment?
Select one:
a. BP
b. BX
c. SP
d. IP
e. CS
Feedback
The correct answer is: SP
11.If AX=7722, BX=2255, CX=C423, SP=3328. What are the contents of BX after the
following code is executed
PUSH AX
PUSH BX
POP CX
Select one:
a. 3326
b. 3328
c. C423
d. 2255
e. 7722
The correct answer is: 2255
12.The reason for separating the BIU and EU inside the 8086 CPU was to:
Select one:
a. Implement pipelining
b. Any part can be easily replaced if it breaks down
c. Be compatible with the 8088
d. Split 16 bit registers to 8 bits
e. Calculate the physical address.
The correct answer is: Implement pipelining
13.MOV DH,CH is a legal operation.
Select one:
True
False
The correct answer is 'True.'
14.If AX=2255, BX=7722, CX=C423, SP=3328. What are the contents of CX after the
following code is executed
PUSH BX
PUSH AX
POP CX
Select one:
a. 3326
b. 2255
c. 3328
d. 7722
e. C423
The correct answer is: 2255
15.If ADD AX,BX is executed, the value of the parity flag will depend whether the
number of zeros is odd or even.
Select one:
True
False
The correct answer is 'True.'
16.When using high level programming language, the programmer must know all the
internal details of the CPU, including the register sizes, memory capacity, and
instruction details.
Select one:
True
False
The correct answer is 'False.'
17.MOV FR,2255H is a legal operation.
Select one:
True
False
The correct answer is 'False'
1. ADD *BX+,*0220+ is a legal
operation. Select one:
True
False
The correct answer is 'False'.
2. If CS=82B6H and IP=434AH, what is the Physical address?
Select one:
a. 434AH
b. 92B5FH
c. 86EAAH
d. 82B60H
The correct answer is: 86EAAH
3. The most significant part of the address bits are sent out on lines through A16 – A19.
Select one:
True
False
The correct answer is 'True'.
4. The status of the PF after the execution the following instructions is 1:
MOV CX, 173FH
MOV AX, 8A9EH
ADD AL, CH
ADD
CH, AL
Select one:
True
False
The correct answer is 'True'.
5. The 16 bit flag of 8086 microprocessor is responsible to indicate
Select one:
a. The condition of memory
b. The condition of result of ALU operation
c. The result of addition
d. The result of subtraction
The correct answer is: The condition of result of ALU operation
6. The microprocessor determines whether the specified condition exists or not by testing
the carry flag.
Select one:
True
False
The correct answer is 'False'
7. Given that SS=2400, SP=8631H, AX=4FA6H, and DX=8C3FH.
The contents of registers AL=3FH, DH=4FH and SP=8632H after the execution of the following
lines of instructions
PUSH
AX
PUSH DX
POP
AX
POP DX
Select one:
True
False
The correct answer is 'False'.
8. Suppose that before the following code is executed the top of the stack
SP=1402H MOV AX,1
MOV BX,2
MOV CX,3
Rep: MUL BL
PUSH AX
DEC CX
JNZ Rep
POP BX
POP CX
POP DX
NOP
What is the content of DX when reaching the NOP instruction.
Select one:
a. 0004H
b. 0008H
c. 1402H
d. 0002H
The correct answer is: 0002H
9. Assume that the registers have the following values (all in Hex) , CS = 1100, DS= 2100,
SS= 3100, SI= 4100, DI= 5100, BX= 6180, BP= 7200, AX= 25FF, CX= 8791, and DX= 1299.
Calculate the physical address of the memory location where the operand is stored for
the following MOV [SI], AL
Select one:
a. 25100H
b. 36104H
c. 25101H
d. 38200H
The correct answer is: 25100H
10. The status of the PF after the execution the following instructions is 1:
MOV CX, 173FH
MOV AX, 8A9EH
ADD AL, CH
ADD
CH, AL
Select one:
True
False
The correct answer is 'True'.
11. Given that SS=2800, SP=8631H, AX=4FA6H, and DX=8C3FH. The physical address of the
memory location pointed by the stack pointer after execution of the following lines of
instructions is 2C631H.
PUSH
AX
PUSH
DX
POP
AX
POP
DX
Select one:
True
False
The correct answer is 'False'.
12. The index register are used to hold
Select one:
a. offset address
b. segment memory
c. offset memory
d. memory register
The correct answer is: offset address
13. Given that SS=2400, SP=8631H, AX=4FA6H, and DX=8C3FH.
The contents of registers AL=3FH, DH=4FH and SP=8631H after the execution of the following
lines of instructions
PUSH
AX
PUSH DX
POP AX
POP DX
Select one:
True
False
The correct answer is 'True'.
14. The 8086 fetches instruction one after another from stack segment of memory.
Select one:
True
False
The correct answer is 'False'
15. The physical address of the stack is obtained by SS: SP combination.
Select one:
True
False
The correct answer is 'True'.
16. Suppose that before the following code is executed the top of the stack SP=1402H
MOV AX,1
MOV BX,2
MOV CX,3
Rep: MUL BL
PUSH AX
DEC CX
JNZ Rep
POP AX
POP BX
POP CX
POP DX
NOP
What is the value of SP when reaching the NOP instruction.
Select one:
a. 1404H
b. 0008H
c. 1402H
d. 1406H
The correct answer is: 1402H
17. "In minimum mode of the 8086, AD0-AD15 lines are multiplexed, while A16-A19 are
not" This claim is:
Select one:
a. Always incorrect
b. Some times correct, depending on the case
c. Always correct
d. Cannot be determined, and requires more information
The correct answer is: Always incorrect
18. The status of the CF after the execution the following instructions is 1:
MOV CX, 173FH
MOV AX, 8A9EH
ADD AL, CH
ADD
AX, AX
Select one:
True
False
The correct answer is 'True'.
19. A 20-bit address bus can locate 1,048,576 locations.
Select one:
True
False
The correct answer is 'True'.
20. If CS = 0701H, SS = 0801H, SI = 0100H and IP = 0108H the address of the next instruction
is 07110H.
Select one:
True
False
The correct answer is 'False'.
21. The" PUSH source" instruction copies a word from source to the stack.
Select one:
True
False
The correct answer is 'True'.
22. The microprocessor determines whether the specified condition exists or not by its flag.
Select one:
True
False
The correct answer is 'True'.