Computer System Hardware, Computer Hardware, RISC and CISC, Instruction Pipelining, Instruction Format and many more fundamental things.

1. The Computer System Hardware
Apart From Computer Software
Er. Sharad Kafle

2. Introduction
Er. Sharad Kafle

3. Central Processing Unit
Er. Sharad Kafle

4. Memory Unit
 They are internal storage areas in a computer
 In the form of chips
 Two Categories : RAM and ROM
RAM (Random Access Memory):
 Holds the data as long as electric supply is on. (volatile).
 Two Basic Types
i) Dynamic RAM : needs to be refreshed
ii) Static RAM : less often refreshed, expensive
ROM (Read Only Memory):
 Non-Volatile
 Program stored in ROM is FIRMWARE programed by manufacturer.
 Eg. Program that boots the computers are stored here.
Er. Sharad Kafle

5. Instruction Format
 An Instruction is normally made up of a combination if an operation
code and some way of specifying an operand, most commonly by its
location or address in memory.
Er. Sharad Kafle

6. Instruction Set
FEW EXAMPLES
ADD - Add two numbers together. || ADD R4, R3 :: R4  R4 + R3
COMPARE - Compare numbers.
IN - Input information from a device, e.g. keyboard.
JUMP - Jump to designated RAM address.
JUMP IF - Conditional statement that jumps to a designated RAM address.
LOAD - Load information from RAM to the CPU.
OUT - Output information to device, e.g. monitor.
STORE - Store information to RAM.
Er. Sharad Kafle

7. Instruction Cycle
 Sometimes called fetch decode cycle.
 It is basic operational process of computer in which a computer retrieves
a program instruction from its memory that determines what actions the
instruction indicates and carries out those action.
 FETCH  DECODE  EXECUTE
Er. Sharad Kafle

8. Instruction Cycle
Er. Sharad Kafle

9. Microprocessor
 Incorporates the functions of a computer’s Central Processing Unit
(CPU) on a single Integrated Circuit (IC).
 Intel, atmel, hp, ARM, NVIDIA,
 Illustration of Example from TextBook.
Er. Sharad Kafle

10. Interconnection : Buses
Er. Sharad Kafle

11. Interconnection : Buses
 BUS is a set of electronic signal pathway that allows information and
signals to travel between components inside or outside of a computer.
 The different components of computer i.e. CPU, I/O and MU are
connected each other by a bus.
 The data, instructions and the signals are carried between the different
components via a bus.
 The command to access the memory or the I/O is carried by a control
bus.
 The address of I/O device or memory is carried by a address bus.
 The data to be transferred is carried by the data bus.
Er. Sharad Kafle

12. Inside a Computer Cabinet
 Modern Computer Consist of three basic section:
 A Processor
 Some Memory
 I/O (Peripheral) Devices
Er. Sharad Kafle

13. Before RISC Vs CISC
Speeding Up
 Memory Mapped I/O
 I/O Processors
 Memory Cache
Er. Sharad Kafle

14. RISC Vs CISC
RISC – Reduced Instruction Set Computer
 Less Space and Shorter design cycle.
 Use of pipelining for immense processing power.
Advantages:
 Speed : Due to simplified instruction
 Simpler Hardware : Less Chip space
 Shorter Design Cycle : Short Machine Cycle.
Er. Sharad Kafle

15. RISC Vs CISC
CISC – Complex Instruction Set Computer
 Uses Microcode.
 Build Rich instruction set and Build high-level instruction set.
Features:
 Several special purpose registers
 Few general purpose registers.
 Single instruction to support multiple addressing mode.
Er. Sharad Kafle

16. An Ideal CISC Machine
 An instruction is fetched from the memory
 The instruction is decoded.
 The instruction is executed
 The results are written in the memory.
CISC Processors are designed to execute instruction completely before
beginning the next instruction :: No PIPELINING
Er. Sharad Kafle

17. Instruction Pipelining
Er. Sharad Kafle

18. Example (RISC/CISC)
LOAD R1, A
LOAD R2,B
PROD A, B
STORE R3, A
MULT A,B  In CISC (One Complex instruction)
 In RISC (Number of fewer simple instruction)
Er. Sharad Kafle

19. Thanks!
Er. Sharad Kafle
Institute of Engineering, Tribhuwan University
Web : www.skafle.com.np
FB : www.facebook.com/kaflesharad
Email : kaflesharad@hotmail.com
kaflesharad@rocketmail.com