Assembly Language in Intel 8086 Architecture

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Questions and Answers

What is the primary function of a register in a CPU?

To perform arithmetic and logical operations

To control the flow of program execution

To store data temporarily while executing instructions (correct)

To provide a direct interface to the external memory

What does the operation code in a machine instruction identify?

The memory location to be accessed

The type of operation being performed (correct)

The destination register for the operation

The source operand for the operation

What is the purpose of a mnemonic in assembly language?

To assist the memory in remembering a CPU instruction (correct)

To indicate the start of a program

To define the format of a data item

To specify the memory location for data storage

How many operands can an instruction contain?

Zero, one, or two operands Signup and view all the answers

What is the advantage of using assembly language over machine language?

Assembly language makes programming easier than machine language Signup and view all the answers

What is the format of an assembly language statement?

[name] [mnemonic] [operands] [;comment] Signup and view all the answers

What is the purpose of an assembler in the context of assembly language?

To translate assembly language into machine language Signup and view all the answers

What is the primary advantage of using assembly language over high-level languages?

Faster execution and more direct access to hardware features Signup and view all the answers

What is the primary purpose of data definition directives in assembly language?

To create storage at assembly time and initialize variables Signup and view all the answers

Which of the following instructions is an example of direct addressing mode?

MOV [2000h], AX Signup and view all the answers

What is the instruction set of a CPU?

A set of machine language instructions specific to a CPU Signup and view all the answers

What is the significance of the AL register in the example machine instruction 00000100?

It is the destination register for the addition operation Signup and view all the answers

What is the main difference between direct and indirect addressing modes?

The way the effective address is specified Signup and view all the answers

What is the attribute of a variable defined using the DW directive?

Word Signup and view all the answers

What is the primary purpose of assembly language in the context of computer systems?

To enable direct access to hardware features and understand the operations of the PC Signup and view all the answers

What is the purpose of the MOV DX, [1234h] instruction?

To move the contents of the memory location 1234h to the DX register Signup and view all the answers

What is the role of the CPU in executing machine instructions?

It executes machine instructions according to their defined meaning Signup and view all the answers

What determines the instruction set of a CPU?

The type of CPU manufactured Signup and view all the answers

What is the size of the attribute defined using the DQ directive?

8 bytes Signup and view all the answers

What is the significance of assembly language in understanding computer systems?

It enables understanding of the way the computer's hardware and OS work together Signup and view all the answers

What is the purpose of the DB directive in assembly language?

To create storage for a byte or group of bytes and optionally assign starting values Signup and view all the answers

Which register is used in the indirect addressing mode instruction MOV AL, [BX]?

BX Signup and view all the answers

Study Notes

Introduction to Assembly Language

Assembly Language (AL) is a specific set of instructions for a particular computer system.
AL teaches you about the way the computer's hardware and OS work together and how application programs communicate with the OS.
AL is a programming language with a one-to-one correspondence between its statements and a computer's main machine language.

Assembly Language and Assembler

An Assembler is a program that translates a program written in assembly language into machine language, which may be executed by the computer.
The Assembler runs under the disk operating systems MS-DOS or PC-DOS.

Machine Instructions

A machine instruction is a binary code that has a special meaning for a computer's CPU, telling the CPU to perform a task.
Each machine instruction is precisely defined when the CPU is constructed and is specified to that type of CPU.

Assembly Language Instructions

Assembly Language is a low-level language because it is close to machine language in structure and function.
Each assembly language instruction corresponds to one machine instruction.
A typical 2-byte IBM-PC machine instruction consists of an operation code and an operand.
Registers are high-speed storage locations inside the CPU used by nearly every instruction.

Assembly Language Statement

An assembly language statement consists of [name], [mnemonic], [operands], and [;comment].
Mnemonic is a short alphabetic code that assists the memory in remembering a CPU instruction.
Operand is an instruction that may contain zero, one, or two operands.

Memory Addressing Mode

There are two types of memory addressing modes: direct and indirect.
Direct Addressing Mode: the effective address is given in the instruction itself, and the transfer is between a register and a memory address.
Indirect Addressing Mode: the name of the base register or the name of the index register is specified in the instruction, and the transfer is between a register and a memory address specified in one or two registers.

Data Definition Directives

Data definition directives create storage at assembly time and can even initialize a variable to a starting value.
Examples of data definition directives include DB (define byte), DW (define word), DD (define doubleword), DQ (define quadword), and DT (define 10 bytes).
The attribute of a data definition directive is the basic unit of storage used when the variable was defined.

Data Definition Directives (Examples)

The DB directive creates an 8-bit variable and initializes it to a starting value.
Example: char db 'A' creates an 8-bit variable called char and initializes it to 41h (ASCII code for the letter A).

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Description

This quiz covers the basics of assembly language, including its elements and addressing modes, as well as how it interacts with computer hardware and the operating system.