ASSEMBLY LANGUAGE PROGRAMMING

Course Objectives Identify the major component of a PC-based system, describe the steps involving in assembling, linking, and executing a program Write/Debug programs in assembly language to perform the given task and run them

Textbook/Technology requirement Textbook: IBM PC Assembly Language and Programming. Peter Abel Fifth Edition. Prentice Hall. ISBN: X Software: Emu8086 microprocessor assembler and emulator software. Available at

Introduction Tell me about yourself and what you expect to get out from this course

Course detail - Topics Write a program in assembly language Understanding of a PC-based system Fundamentals of assembly language & program Specific Applications

What does it take to success -Attend the class regularly and actively participate in the class discussion (ask questions, answer questions, etc..) -Don’t give up on programming assignments. Pay attention to detail -Try many options when doing programming assignments

Questions?

Overview Fundamental of PC Hardware and Software

Basic features of PC Hardware Binary and Hexadecimal Number Systems –Bits/bytes –Binary number systems –Hexadecimal –ASCII PC Components –Processor –Memory

Bits/bytes and Binary system Bits: 0(off) & 1(on) Bytes: –Represents a storage location in memory and devices. –8 bits => 2 8 combination of 0/1.

Bits/bytes and Binary system Address 40 Husky Road Storrs, CT Word Doubleword Quadword Paragraph Kilobyte Megabyte

Bits/bytes and Binary system Bit value Position value Bit number Operations 0+0=0 1+1=10 1+0=1 Negative binary numbers 2’s complement’s notation Reverse the bit values and add Add

1. What is the value of ? 2. How to represent -25 in 2’s complement notation?

Bits/bytes and Binary system Bit value Position value Bit number Parity bit: forcing the number of bits always odd Example: Parity bit = Parity bit = 0

Hexadecimal presentation Disadvantage of binary representation: –Is not “user-friendly” –Complicated when computing manually Hexadecimal representation

Hexadecimal presentation Hexadecimal arithmetic 7+1=8 7+2=9 7+3=A 7+4=B 7+8=F 7+9=?

Practice Convert from decimal to hexadecimal 23 = ???? 254 = ???? Adding hexadecimal value 13B4H H = ???? DCBEH + 35B5H = ????

Popular coding systems to represent data  ASCII—American Standard Code for Information Interchange  EBCDIC—Extended Binary Coded Decimal Interchange Code  Unicode—coding scheme capable of representing all world’s languages

Conversion from letter to binary format and back Step 1. The user presses the capital letter D (shift+D key) on the keyboard. Step 2. An electronic signal for the capital letter D is sent to the system unit. Step 3. The signal for the capital letter D is converted to its ASCII binary code ( ) and is stored in memory for processing. Step 4. After processing, the binary code for the capital letter D is converted to an image, and displayed on the output device.

Question?

PC Components printer scanner speaker PC camera microphone digital camera system unit keyboard modem speaker monitor mouse

PC Components Central Processing Unit (CPU) Also called a processor Carries out instructions that tell computer what to do Memory Temporary holding place for data and instructions

Central processing unit (CPU) (Processor)  Interprets and carries out basic instructions that operate a computerProcessor Control Unit Arithmetic Logic Unit (ALU) Input Devices Storage Devices Output Devices Memory DataInformation Instructions Data Information Control Unit  Control unit directs and coordinates operations in computer  Arithmetic logic unit (ALU) performs arithmetic, comparison, and logical operations

Memory Operating system Applications Data Three basic items stored in memory Temporary storage place for data, instructions, and information Consists of one or more chips on the motherboard or some other circuit board

Memory  Size of memory is measured by the number of bytes available Kilobyte - 1,024 bytes Megabyte – approximate one million bytes

Volatile Memory Loses its contents when the computer's power is turned off volatile memory Loses its contents when the computer's power is turned off Memory What are the two types of memory in the system unit? nonvolatile memory Does not lose its contents when the computer’s power is turned off

Memory Memory chips that can be read from and written to by the processor and other devices When the computer starts, operating system files are loaded from a hard disk into RAM What is random access memory (RAM)? As additional programs and data are requested, they also load from storage into RAM Most RAM is volatile

Addressing data in Memory Difference between address of a memory Location and its content Processor stores the data in memory in reverse by sequence Two types of addressing schemes absolute address segment-offset address

Segment Code segment (CS) Data segment (DS) Stack segment (SS) Extra segment (ES) Actual address = segment address + offset

Registers Segment register –CS,DS,SS,ES, FS and GS Pointer register –IP,SP,BP General purpose register –AX,BX,CX,DX Index register –SI, DI

Flags OF, DF, IF, SF, ZF,AF,PF,CF If cleared: NV,UP,EI,PL,NZ,NA,PO,NC If set: OV,DN,EI,NG,ZR,AC,PE,CY