Introduction to Assembly Language Q2. Which are valid MASM statements? If none,

Question

Introduction to Assembly Language
Q2. Which are valid MASM statements? If none, explain why.
a. x byte 10 dup(?)
b. y dword 1, 2, 3
c. mov x, y
d. mov 20, AL
e. mov [ESI + EBX * 8 + offset x], AL
f. How many times does this loop?
L1: mov ecx, 10
dec ecx
jnz L1

g. What is the difference between real mode and protected mode?
h. Which mode does windows use?

i. Write a shift instruction that divides a signed integer in ECX by 8.
j Write a sequence of instructions that divide -16 by 5 using the IDIV instruction.Use the EBX register as the divisor.
k. write a sequence of two instructions that copies bits 0-5 from AL to bits in BL. Bits 6-7 in BL should be cleared, and AL should be unchanged.

L. What advantages does INVOKE offer over the CALL instruction.

Explanation / Answer

Q) Which are valid MASM statements? If none, explain why.

Valid Statements:

Invalid Statements:

g) Differences between Real mode & Protected Mode

ans)

Real Mode

Protected Mode

h) Which mode does windows use?

Ans) Windows/386 uses the virtual 8086 mode of Intel 80386 to multitask several DOS programs and the paged memory model to emulate expanded memory using available extended memory. Windows/286, in spite of its name, runs on both Intel 8086 and Intel 80286processors. It runs in real mode but can make use of the high memory area.

L) What advantages does INVOKE offer over the CALL instruction.

Ans)

Real Mode

Protected Mode

• Only one job at a time

• Multiple jobs at a time (Multitasking)

• It only addresses only upto 1MB of RAM

• It addresses 16MB of RAM

• Real Mode Drivers run under DOS operating system

• Protected mode Drivers run under windows3.x

• In Real Mode, software directly communicates directly with computer port’s and devices.

• The System ports are protected from the applications that use them.

• It is a 16 bit

• It is a 32 Bit

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