ICS 312 Set 2

1. ICS 312 Set 2 Microcomputer Systems

2. Uses of Assembly Language Programming: • To understand the architecture of computers • Critical code sections in programs written in other languages for applications such as Excel. • Drivers for printers, hard disks, etc. • Games • Graphics • Compilers (also critical code sections)

3. Components • digital circuits • binary digits • cpu • memory circuits • motherboard • expansion slots • peripheral devices

4. Memory memory operations • read • Write • RAM • ROM • buses • address bus • data bus • control bus

5. The CPU • external bus • internal bus • ALU • IP • machine language • instruction set

6. Ports • serial port • parallel port • USB

7. Instruction Execution • machine instruction • opcode • operands • fetch-execute cycle • clock timing

8. Programming Languages • Machine Language • Assembly Language • assembler • High-Level Languages • compiler

9. Examples of Pentium instructions: 1. Move a byte from memory to an internal register within the Pentium. 2. Add a number encoded in 2 bytes to an internal register. Typically a single C instruction is transformed by a C compiler into many assembler or machine code instructions. Example: In C: int x = 5, y = 7, z; z = x + y;

10. Equivalent code in assembler TITLE EXAMPLE FOR ICS 312 .MODEL SMALL .STACK 100H ; declares the size of the hardware stack ; data comments begin with semi-colons .DATA X DW 5 Y DW 7 Z DW ? ; value is uninitialized .CODE MAIN PROC ; mysterious 2 lines to be explained later MOV AX,@DATA MOV DS,AX ; add the numbers MOV AX, X ; AX has X ADD AX, Y ; AX has X+Y MOV Z, AX ; Z = X+Y ; code to end the program ; also to be explained later MOV AX,4C00H INT 21H MAIN ENDP END MAIN

11. Textbook Reading (Jones): Chapter 1.