Computer Views

1. Computer Views Computer ArchitectureCS 215

2. Some terms • K (kilo) = 210 = 1,024 • M (mega) = 220 = 1,048,576 • G (giga) = 230 = 1,073,741,824 • T (tera) = 240 = ???

3. Viewpoints • User • Programmer • Architect • Logic Designer

4. User’s View • Often called end-user • Does not see implementation, only end results

5. Programmer’s View • Functional behavior of a computer as viewed by a programmer • Instruction Set Architecture (ISA) • Functional units • Data type sizes, operations, etc.

6. Instruction Classes • Data movement • Arithmetic/Logic • Control flow

7. More terms • Machine state • Contents of all registers and machine memory • Procedure calls • Used to implement functions • Machine interrupts • Unexpected interruptions to normal execution • Exceptions • Internal problems with normal execution

8. Architect’s View • Structural relationships that are not visible to the programmer • Driven by performance needs & csot constraints • Interfaces, clock frequency, memory, etc.

9. Logic Designer’s View • Works in both Boolean logic and implementation • Concerned with … • Design correctness • Constraints • Ex. Fan-in and Fan-out • Uses various design and analysis tools

10. Von Neumann Model Memory Unit • Input Unit • Provides instructions and data to system Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

11. Von Neumann Model Memory Unit • Output Unit • Returns data from system Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

12. Von Neumann Model Memory Unit • Memory • Storage for instructions and data Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

13. Von Neumann Model Memory Unit • ALU • Processes data Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

14. Von Neumann Model Memory Unit • Control Unit • Directs processing Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

15. Von Neumann Model Memory Unit • CPU • ALU and Control Unit combined CPU Input Unit Arithemtic and Logical Unit (ALU) Output Unit Control Unit

16. System Bus Model • Streamlined version of von Nuemann model • Data Bus • Address Bus • Control Bus • Power Bus (optional) CPU (ALU, Registers, & Control) Memory Input & Output (I/O) Data Bus Address Bus System Bus Control Bus

17. System Bus Model • Data Bus • Carries the information being transmitted • Sometimes implemented as data-in and data-out buses CPU (ALU, Registers, & Control) Memory Input & Output (I/O) Data Bus Address Bus System Bus Control Bus

18. System Bus Model • Address Bus • Identifies where the information is being sent • “Memory” address identifies read/write location CPU (ALU, Registers, & Control) Memory Input & Output (I/O) Data Bus Address Bus System Bus Control Bus

19. System Bus Model • Control Bus • Describes aspects of how the information is being sent, & in what manner CPU (ALU, Registers, & Control) Memory Input & Output (I/O) Data Bus Address Bus System Bus Control Bus

20. Machine Levels User or Application Program Level • Each level represents an abstraction of the computer • Levels are kept relatively independent from one another • Can allow for upward compatibility High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

21. User or Application Program Level User or Application Program Level • User interacts with computer High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

22. High-Level Language Level User or Application Program Level • Compiler maps data types and instructions to actual computer hardware • Can be recompiled in different environments • Source code compatibility High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

23. Assembly Language / Machine Code Level User or Application Program Level • Language of the computer • Instruction sets • Assembler substitutes instruction codes for mnemonics • Different hardware can support same instruction set High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

24. Control Level User or Application Program Level • Effects register transfers • Control signals transfer data from register to register • Hardwired Vs. Microprogram control • firmware • microcontroller High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

25. Functional Unit Level User or Application Program Level • Internal CPU registers • ALU • Computer’s main memory High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

26. Logic Gates, Transistors & Wires User or Application Program Level • The hardware! • (More on this later) High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

27. Question? User or Application Program Level • Which levels map to which views? High-Level Language Level Assembly Language / Machine Code Level Control Level Functional Unit Level Logic Gates Transistors & Wires

28. Machine Levels • Floating point emulation • Due to insufficient resources • Floating point instructions are trapped • Replaced with machine code to imitate floating point instructions • Emulation Vs. Math coprocessor

29. Typical Computer System • Input • Keyboard • Output • Monitor • Storage • Floppy disk, hard disk, CD-ROM, etc. • Motherboard • CPU, RAM, expansion slots, bus, etc.