Question

Q17. Fill in the blanks:

Consider the operands to be signed words (16 bit)

a) mov ax, - 48 cwd mov bx , 5 idiv bx ; ax = _______ , dx = _____ (provide answers in decimal) Consider the operands to be signed words (16 bit)

b) mov ax , -1 mov bx , -1 imul bx ; ax = _________H, dx =__________H (provide answer in Hex) Consider the operands to be signed words

c) mov ax , -1 mov dx , 2 imul dx ; ax = _______H ,dx = ________H(provide answer in Hex) Consider the operands to be signed byte (8 bit)

d) mov al, -48 cbw mov bl, 5 idiv bl ; al = _____, ah = _______ (provide answers in decimal) 5

Q18. Fill in the values as the following code fragment is executed:

a) count DB 9A H ; count is Byte variable initialized to 9A H num DB BC H ; num is a Byte variable initialized to BCH mov ah, count mov al, num ; ax = _______________H

b) mov ax, 1234H mov ax, ‘A’ ; ax = ________________H (Hint: ASCII code of ‘A’ = 65 in decimal)

c ) mov dx , 0087H mov ax, 6000H mov bx, 100H div bx ; ax = ________________H

d) mov ax, 1237H sub al, 38H ; ax = ________________H

Answer 1

a) mov ax, - 48

cwd

mov bx , 5

idiv bx ; ax = -9 , dx = -3  

Ans. IDIV performs signed integer division

b) mov ax , -1

mov bx , -1

imul bx ;    ax =00000001 H, dx =00000000H

Ans. IMUL performs multiplication if 8,16,32 bit data with either AL, AX or EAX. Preserves sign of product by sign extending it into upper half of destination register.

c) mov ax , -1

mov dx , 2

imul dx ; ax = FFFFFFFE H ,dx = 00000000H

Ans. IMUL performs multiplication if 8,16,32 bit data with either AL, AX or EAX. Preserves sign of product by sign extending it into upper half of destination register.

d) mov al, -48

cbw

mov bl, 5

idiv bl ; al = -9 , ah = -3

Ans. IDIV performs signed integer division

Q18. Fill in the values as the following code fragment is executed:

a) count DB 9A H ; count is Byte variable initialized to 9A H

num DB BC H ; num is a Byte variable initialized to BCH

mov ah, count

mov al, num ; ax = 9ABC H

Ans. Here data of count variable is stored in higher byte of Accumulator (ah) and data of num variable is stored at lowwer byte of Accumulator (al). Hence 2 datas are stored in one register.

b) mov ax, 1234H

mov ax, ‘A’ ; ax = 1241 H (Hint: ASCII code of ‘A’ = 65 in decimal)

c ) mov dx , 0087H

mov ax, 6000H

mov bx, 100H

div bx ; ax = 8760 H

d) mov ax, 1237H

sub al, 38H ; ax = 12FF H