Assembly Language Memory Operations

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Questions and Answers

What value is stored in memory location 1000:0400H after executing all instructions?

0FFH

07H

00H

04H (correct)

What is the purpose of the instruction 'MOV DX, 1000H' in the provided instructions?

To prepare the offset address for memory operations.

To load the value into the accumulator.

To clear any previous values in the register.

To set the data segment to the address 1000H. (correct)

Which instruction is responsible for swapping the values at memory locations 1000:0400H and 1000:0402H?

MOV DL, [SI]

XCHG AX, [SI] (correct)

MOV [SI], OFFH

XCHG AX, [DI] (correct)

What are the final values at memory locations 1000:0400H and 1000:0402H after all instructions have executed?

04H and 07H respectively. Signup and view all the answers

Which instruction is used to clear the DX register before loading the value into DL?

XOR DX, DX Signup and view all the answers

In the first program, what is stored in memory location [0402H]?

04H Signup and view all the answers

What is the purpose of the MOV ES, AX instruction in the second program?

To load the segment register with the base address. Signup and view all the answers

In the third program, how are negative numbers identified?

By checking the sign flag after loading into AL. Signup and view all the answers

What value is recorded in DH at the end of the third program if the inputs contain three negative numbers?

3 Signup and view all the answers

What is the initial value stored at memory location [0400H] in the fourth program?

0AH Signup and view all the answers

Which instruction increments the source index (SI) register in the third program?

INC SI Signup and view all the answers

What is the purpose of the LOOP instruction in the second program?

To decrement the counter and jump if not zero. Signup and view all the answers

What does the instruction MOV AL, [SI] do in the context of the fourth program?

Loads the next value from the data segment into AL. Signup and view all the answers

After executing the instruction 'MOV AX, 2345H', what values are stored in the AX register?

2345H Signup and view all the answers

What is the value of the AX register after the execution of the 'ADD AX, BX' instruction?

8A CE Signup and view all the answers

What happens to the CF (Carry Flag) after executing the instruction 'SUB AX, BX'?

It is set to 1. Signup and view all the answers

What is the value of the AL register after executing the instruction 'NOT AL'?

00 CA Signup and view all the answers

Which instruction modifies the BL register to hold the value 00H?

MOV BL, 00H Signup and view all the answers

What is the final value of the AL register after the instruction 'DAA' is executed?

00 10 Signup and view all the answers

What is indicated by the status of the Zero Flag after the instruction 'DIV CL' is executed?

The result is non-zero. Signup and view all the answers

What does the 'ADC AL, BL' instruction do with the contents of AL and BL?

Adds AL and BL with carry from previous operation. Signup and view all the answers

What is the purpose of the XOR instruction used at the beginning of the programs?

To reset registers to zero Signup and view all the answers

In the program that counts even and odd numbers, what does the AND operation achieve?

It is used to mask the least significant bit to determine even or odd Signup and view all the answers

What happens when the JC (Jump if Carry) instruction is executed?

Control moves to the specified label if the carry flag is set Signup and view all the answers

In the string copy program, what is the purpose of the CLD instruction?

To ensure strings are copied to lower memory addresses Signup and view all the answers

How is the smallest number determined from a series of numbers in the program?

By repeatedly updating a register with numbers less than a current value Signup and view all the answers

What is the function of the LOOP instruction in the given assembly programs?

To count down the CX register and repeat until it reaches zero Signup and view all the answers

In the context of the assembly language provided, what does the MOV instruction generally accomplish?

It transfers data from one location to another Signup and view all the answers

What does the REP MOVSB instruction do in the string manipulation program?

It repeats a single byte operation until a condition is met Signup and view all the answers

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Study Notes

Experiment 1

The experiment involves writing down the results of affected flags stored in the registers after each instruction.
Instructions are listed, each with a corresponding register status.
The status includes registers such as CS, BX, CX, DX, Flag register (AH, AL, BH, BL, CH, CL, DH, DL, OF, SF, ZF, AF, PF, SF, CF).

Experiment 2

The data from memory location 1000:0400H is read and stored in register DL.
The instruction includes moving data to DS and SI.
The process involves XOR operations, and moving values to given memory locations.

Experiment 3

The contents of memory locations 1000:0400H and 1000:0402H are exchanged.
Instructions involve moving data to AX, DS, and specific memory locations (0400H, 0402H).
Specific arithmetic operations (AND, OR, XOR, NOT etc) are involved.

Experiment 4

Results for various instructions, notably MOV, ADD, and AAA, are detailed
Results are presented showing register values (AX, BX) after each instruction.

Experiment 5

Instructions involve BCD arithmetic operations using AAA, AAD, and AAM.
Example instructions given as MOV, ADD, MOV, MUL, and AAM.
The results demonstrate the arithmetic results in unpacked BCD format.

Experiment 6

Instructions read from a memory location (1000:0400H).
The data is stored in the DL register.
Various instructions such as MOV, MOV, XOR, MOV and HLT are used.

Experiment 7

The experiment aims to count odd and even numbers from a given series of 10 unsigned numbers.
The count for even numbers is stored in DL and odd numbers in DH.
Instructions include MOV, INC, LOOP, AND, and HLT.

Experiment 8

Instructions read data from 1000:0100H memory address and store the result in DX register.
The instructions used include MOV, PUSH, POP, XOR, INC, and LOOP.

Experiment 9

The experiment aims to find the smallest number from a given series of 10 unsigned numbers stored in memory.
The result is stored in the DL register.
Instructions given in the table includes MOV, XOR, CMP, INC, LOOP, and JMP.

Experiment 10

The 2's complement of a number stored at memory location 1000:0400H is calculated.
The result is stored in the DL register.
Instructions include MOV, XOR, NEG, and HLT.

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Description

This quiz focuses on understanding assembly language instructions related to memory operations. Participants will analyze how specific instructions affect values stored in memory locations. Test your knowledge on MOV, SWAP, and clearing registers in assembly language programming.