COMPSCI 1210 LAB A

A programming language that can be directly understood and obeyed by a machine or computer without any translation.

Machine Language

a low-level programming language for a computer or other programmable device specific to a particular computer architecture in contrast to most high level programming languages, which are generally portable across multiple systems.

Assembly language

simple computer model

The __ connects the various components of a computer.

system bus (shown in yellow)

The __is the heart of the computer, most of the computations occur inside the CPU.

CPU

__ is a place to where the programs are loaded in order to be executed.

RAM

Why Assembly Language? (enumerate all the benefits)

* Speed
* Space
* Capability
* Knowledge

Assembly language programs are generally the fastest programs around.

Speed

Assembly language programs are often the smallest

SPACE

You can do things in assembly which are difficult or impossible in HLLs

Capability

Your knowledge of assembly language will help you write better programs, even when using HLLs

Knowledge

Representation of Numbers in Binary

* **1 BIT** - (either 1 or 0)
* **NIBBLE(4)** - 1 nibble is equal to four bits or half a byte (maximum value of Fh, 15 decimal).
* **1 BYTE(8) -**

1 byte is equal to 8 bits or 2 nibbles
(maximum value FFh, 255 decimal)
* **1 WORD (16) -**

1 word is equal to 2 bytes

__ are a place in the CPU where a **number can be** **stored and manipulated.**

Registers

There are three sizes of registers

* 8-bit intel 8008,
* 16-bit 8086 architechture,
* 32-bit 80386 architecture.

4 different types of registers;

* General Purpose
* Segment
* Stack
* Index

General Purpose Registers

* AX
* BX
* CX
* DX
* SI
* DI
* BP
* SP

the accumulator register (divided into AH / AL). ·

AX

the base address register (divided into BH / BL). ·

BX

\- the count register (divided into CH / CL). ·

CX

* the data register (divided into DH / DL). ·

DX

destination index register.

· DI

source index register

**SI**

\- base pointer.

· BP -

\- stack pointer

SP

* Sometimes called pointer registers
* **Mainly used for string instructions**

Index Registers

Index Registers:

* SI
* DI
* IP

__are used as source index for string operation

Source index

__are also used for string operation

Destination index

___cannot be manipulated directly because it stores the address of the next instruction

Instruction pointer

Stack Registers:

* • BP
* SP

__ is similar to BX, generally used to address and access local variables in a process.

– Base pointer

__maintains the program stack for arithmetic computations

Stack pointer

specific areas defined in a program for containing data, code and stack.

Segment Register

**three main segments** of Segment register:

* Code Segment
* Data Segment
* Stack Segment

It contains all the instructions to be executed.

Code Segment

It contains data, constants and work areas.

Data Segment −

It contains data and returns addresses of procedures or subroutines.

Stack Segment −

* an area of memory which you can save and restore values too.
* This is an area of memory that is like a stack of plates

stack

__ like data structure in the memory in which data can be stored

Stack

the last one you put on is the first one that you take off.

LIFO or FILO

If another piece of data is put on the stock, it grows __.

downward

the stack starts at a __ and grows downwards.

high address

The element that is higher in the stock have ___than those on the bottom

lower address

Stock is comprised of elements that are added and removed with **t**wo operations

Push and Pop

PUTS A PIECE OF DATA ONTO THE TOP OF THE STACK.

Push

PUTS THE PIECE OF DATA FROM THE TOP OF THE STACK INTO
A SPECIFIED REGISTER OR VARIABLE.

Pop

syntax for push

syntax for pop

3 types of operand

* Immediate
* register
* memory

___is a number which will be known at compilation and will always be the same

Immediate operand

___ any general purpose or index register. Example AX or SI.

Register operand

___is a variable which is stored in memory.

Memory operand

ASSEMBLY INSTRUCTION

Most instructions are made up of **three characters**

* operand
* comma
* another operand

moves a value from one place to another.

MOV

__ calls a DOS or BIOS function which are subroutines to do things that we would rather not write a function

INT

Most interrupts have more than__, this means that you have to pass a number to the function you want.

one function

How to declare a data

You can only put bytes into __ registers and word into _ registers

* 8-bit
* 16-bit

add the contents of one number to another

ADD -

subtract one number from another

SUB —

multiplies two unsigned integers (always +)

MUL -

multiplies two signed integers (either + or -)

IMUL —

divides two unsigned integers (always +)

DIV -

divides two signed integers (either + or -)

IDIV —