1. Chapter 6 Programming the basic computer
충남대학교 컴퓨터전공
이 철 훈

2. Tab. 6-1 Computer instructions
Chapter 6
Introduction
Basic computer의 instruction set
Tab Computer instructions
Computer System Architecture 1

3. Chapter 6
Machine Language
Program : a list of instructions or statements for directing the computer to perform a required data-processing task
Programming language types (Tab. 6-2, 3, 4, 5)
1. Binary code : machine language
2. Octal or hexadecimal code : equivalent translation of binary code
3. Symbolic code : assembly language
4. High-level language
Computer System Architecture 1

4. Assembly Language Assembly language program의 각 line은 3가지 field로 구성된다.
Chapter 6
Assembly Language
Assembly language program의 각 line은 3가지 field로 구성된다.
1. label field : empty or symbolic address
2. Instruction field : machine instruction or pseudoinstruction
3. Comment field : empty or comment
Symbolic address
3자까지의 alphanumerical 문자로 구성되며, 첫 자는 반드시 letter이어야 한다.
Comma로 끝난다.
Computer System Architecture 1

5. Assembly Language Instruction field Chapter 6
1. Memory-Reference Instruction (MRI)
2. Register-Reference or I/O Instruction (non-MRI)
3. Pseudoinstruction with or without operand
MRI : 2 or 3 symbolic separated by space
∗ 1st : three-letter symbol defining an MRI opcode
∗ 2nd : symbolic address
∗ 3rd : I or empty
non-MRI : does not have address part
※ Instruction field에 사용된 symbolic address는 level field에 반드시 있어야 한다.
Computer System Architecture 1

6. Tab. 6-2 Definition of Pseudoinstructions
Chapter 6
Assembly Language
Pseudoinstruction : machine instruction이 아니고, assembler에게 정보를 주기 위한 instruction이다
Comments : 설명 목적으로 사용되며 반드시 slash로 시작된다.
Tab Definition of Pseudoinstructions
Computer System Architecture 1

7. Assembly Language Chapter 6 Computer System Architecture 1
Tab Assembly language program to subtract two numbers
Tab Listing of translated program of Tab. 6-8
Tab Address symbol table
Computer System Architecture 1

8. Tab. 6-11 Computer representation of the code line
Chapter 6
The Assembler
Representation of symbolic program in memory
PL3, LDA SUB I
1st Pass : generates address symbol table
Location counter (LC ) : memory location assigned to instruction or operand presently being processed
∗ ORG pseudoinstruction에 의해 초기화된다
Tab Computer representation of the code line
Computer System Architecture 1

9. The Assembler Chapter 6 Computer System Architecture 1
Fig Flowchart for first pass of assembler
Tab Address symbol table for program in Tab. 6-8
Computer System Architecture 1

10. Chapter 6
The Assembler
2nd pass : machine instructions are translated by means of table lookup procedures
1. Pseudoinstruction table
2. MRI table
3. non-MRI table
4. Address symbol table
⇒ 모든 symbol은 이들 table 중 하나에 존재해야 한다.
Error Diagnostics : assembler는 symbolic program에 있는 모든 가능한 error를 검출하여, error message를 출력해야 한다.
MRI나 non-MRI table에 없는 잘못된 machine code symbol
label에 없는 symbolic address, 등등
Computer System Architecture 1

11. Fig. 6-2 Flowchart for second pass of assembler
Chapter 6
Fig Flowchart for second pass of assembler
Computer System Architecture 1

12. Tab. 6-13 Compiled symbolic program to add 100 number
Chapter 6
Program Loops
Program loop : a sequence of instruction that are executed many times, each time with a different set of data (ex. Fortran Do statement)
Computer System Architecture 1
Tab Compiled symbolic program to add 100 number

13. Programming Arithmetic and Logic Operations
Chapter 6
Programming Arithmetic and Logic Operations
Hardware 구현 : 하나의 machine instruction으로 구현된 operation
Software 구현 : 여러 개의 instruction으로 구현되는 operation
Multiplication Program (Fig. 6-3)
Computer System Architecture 1

14. Programming Arithmetic and Logic Operations
Chapter 6
Programming Arithmetic and Logic Operations
Tab Program to multiply two positive numbers
Computer System Architecture 1

15. Programming Arithmetic and Logic Operations
Chapter 6
Programming Arithmetic and Logic Operations
Logic Operations
OR : x + y = (x’y’)’ → DeMorgan’s theorem
Shift Operations
logical shift operations
arithmetic shift operations
Computer System Architecture 1

16. Tab. 6-16 Program to demonstrate the use of subroutine
Chapter 6
Subroutines
Subroutines : a set of common instruction that can be used many times
Tab Program to demonstrate the use of subroutine
Computer System Architecture 1

17. Tab. 6-19 Program to input and output one character
Chapter 6
I/O Programming
Tab Program to input and output one character
Computer System Architecture 1

18. I/O Programming Program interrupt Chapter 6
Programmed I/O 방식에서의 CPU가 I/O device의 상태를 항상 체크해야 하므로 성능면에서 상당히 낭비가 많다. 이를 해결하기 위해서 I/O device가 CPU에게 interrupt를 걸어 I/O를 요청하게 한다 (interrupt 방식)
Interrupt 처리 순서
1. Save contents of processor registers
2. Check with flag is set
3. Service the device whose flag is set
4. Restore contents of processor registers
5. Turn the interrupt facility on
6. Return to the running program
Computer System Architecture 1

19. Tab. 6-23 Program to service interrupt
Chapter 6
I/O Programming
Tab Program to service interrupt
Computer System Architecture 1