1. A P L L LTD
History Of Computing
Computer Hardware

2. Overview
(not from book)
Computer Development
Computer architecture

3. Introduction
Computer is arguably the most important tool in the areas of engineering, science, business etc. etc.
Data acquisition and analysis
Simulation
Embedded applications
Process control
Condition monitoring and fault diagnosis systems
Automatic testing equipment
Robotics
Telecommunications
Productivity software (word processing, spreadsheets, databases, presentation) etc……………

4. Computer development The Abacus- Babylonia-4th century B.C.
The Difference Engine- Charles Babbage 1822
Vacuum tube - John Ambrose Fleming 1904
The ENIAC (Electronic Numerical Integrator and Computer)-1945
Used 17,478 vacuum tubes
Too late for WW-II, but was used in the cold war to perform calculations to build a hydrogen bomb

5. Transistor - Nobel prize in physics in 1956
City of Philadelphia reportedly experienced brown-outs when ENIAC drew power at its home at the the University of Pennsylvania (
Was not a general purpose computer: programming meant rewiring with punch cards and switches
One of ENIAC's greatest feats was in showing the potential of what could be accomplished in the future
Transistor - Nobel prize in physics in 1956

6. Integrated Circuit (chip) - Jack Kilby 1958 (Nobel prize in physics in 2000)
First commercially available IC’s developed by Texas Instruments and Fairchild semiconductor corp.
Generations of IC’s:
Small scale integration
Up to 100 devices on a chip
Medium scale integration - to 1971
100-3,000 devices on a chip
Large scale integration
3, ,000 devices on a chip
Very large scale integration to date
100, ,000,000 devices on a chip
Ultra large scale integration
Over 100,000,000 devices on a chip
Apple I computer (1976)

7. Moore’s Law: Number of transistors on a chip will double every 18 months.

8. Computer Architecture
Central
Processing
Unit
Main
Memory
Systems
Interconnection
Input
Output

9. Components of a Computer System
Storage
(External memory)
input/output
central processing unit
Main Memory
(RAM)

10. Computer Components

11. Component description
Central Processing Unit (CPU) or microprocessor, controls the operation of the computer and performs its data processing functions
Main memory - also called internal memory stores instructions and data. Memory is partitioned into separate instruction and data spaces
Input/output (I/O) – moves data between the computer and its external environment
System interconnection – some mechanism that provides for communications among the CPU, the main memory, and the I/O devices
-CPU is the heart of the computer- also called the microprocessor or processor. Has two main components: the control unit and the ALU. These units work together with the RAM to make the processor and computer function correctly. First developed by Intel in Intel and AMD are leaders in the market for manufacturing microprocessors
-Main memory: RAM and ROM. In the coming slides
-Input/Ouptut, in the coming slides
-System interconnection (optical interconnects)

12. Structure of the CPU storage memory input/output control unit ALU
registers
registers
cache
memory
flags

13. Components of the CPU
Arithmetic and Logic Unit (ALU): processes the data in the registers according to instructions issued by the control unit. Performs arithmetic (addition, subtraction, etc..) and logical (comparison) operations
Registers: provides temporary storage for data and instructions. It handles instructions and data at 10 times the speed of cache memory. Registers facilitate the movement of data and instructions between RAM, the control unit and the ALU
Control unit registers:
The instruction register contains the current instruction being executed
The program register (instruction pointer) contains the RAM address of the next instruction to be executed
ALU registers
The accumulator register stores the result of ALU operations

14. Internal CPU interconnection: some mechanism that provides for communication among the control unit, ALU, and registers
Control Unit: controls the operation of the CPU and hence the computer. Interprets instructions, moves data to/from memory and registers, instructs ALU to perform certain operations, increments instruction pointer, etc. During program execution, instructions in a program are moved from the RAM into the control unit, where it is decoded and interpreted by the decoder
Flags: 1-bit memory, or 1-bit registers and hold information on what has recently happened in the CPU. These are set to 1 or 0 depending on the results of internal operations such as results of ALU operations (zero or negative result) or external operations such as interrupts (commands that tell the processor to stop execution and wait for further instruction)

15. Cache Memory: Small fast memory that improves CPU’s efficiency
Cache Memory: Small fast memory that improves CPU’s efficiency. Increases computer throughput, and is a high-speed holding area for program instructions and data. It holds only instructions and data that are likely to be needed by the CPU. While programs are running on the computer, the same data or instructions might be needed frequently. In such cases, the processor first checks the cache memory for the data or instructions, thereby reducing the need for frequent access to the RAM and speeding up the processing

16. Microprocessor System Buses
RAM
ROM
Control Bus
Microprocessor
(CPU)
Data Bus
Input/Output
(I/O)
Address Bus

17. System Buses
A BUS is an internal communications path consisting of a number of lines connecting the system components
Control bus –The control bus synchronizes system events like memory access, system interrupts, I/O, etc.
Address bus – Source and destination addresses are sent over the address bus to identify a particular location in memory or input/output port.
Data bus – two way path for transferring data and instructions in and out of the microprocessor

18. Main Memory A collection of cells Each cell has an address and a value
Random Access Memory (RAM)
Cells can be accessed randomly
Ram is volatile
All data stored in binary format
Bit, byte and word are the unit of data

19. Main Memory
RAM – Random Access Memory. Temporary read/write memory. Applications are typically loaded into RAM during computer use. Types of RAM include:
SRAM (static) , DRAM (dynamic ), EDO RAM (extended data out) , SDRAM (synchronous dynamic-most new PC’s are equipped with this RAM which is able to synchronize itself with the processor, enabling data transfer at more than twice the speed of previous RAM technologies)
SRAM is called static because the memory retains its contents as long as power is supplied-It does not have to be periodically refreshed as in DRAM. It is faster than DRAM (The contents of the memory can be read much faster), however is more expensive and is larger in size
DRAM is called Dynamic RAM because the memory content needs to be refreshed periodically (every few milliseconds) due to leakage of electrical charge. It is slower than SRAM, but cheaper and smaller in size
Volatile memory (RAM)
Over the past 2 decades, reserachers have come up with versions of Rams to increase spped of processing. These are SRAM, DRAM, EDO RAM etc…Most new PCs are being equipped with SDRAM (synchronous dynamic RAM) Non-volatile memory: ROM

20. CPU-Memory Interaction
Fetch-execute cycle
LDA 14 1
ADD 15 2
STA 14 3
HLT …. …… 14 10 15 7
Assume a is stored in 14
and b is stored in 15
Program
a= a + b
Result 14 17 15 7

21. ROM – Read Only Memory. ROM can typically be written once, but read many times. It is used to store BIOS (Basic Input/Output System-helps to load and locate an operating system), external to microprocessor, and computer instruction sets, internal to microprocessor
The contents of the ROM are hard wired by the manufacturer in a typical ROM chip. When you turn the computer on, ROM automatically prepares the computer system and loads the initial display screen prompt
A variation of ROM is PROM (Programmable Read Only Memory), in which the user can load programs and data that are read only. This can be done with device called a PROM programmer. Writing to a PROM destroys the internal links, so a basic PROM can only be programmed once

22. EPROMs (Erasable Programmable Read Only Memory) is a variation of PROM, and is rewritable. It can be erased by exposing the chip to ultraviolet light. It can then be programmed with an EPROM programmer
Flash memory is a type of PROM that can be easily altered by the user. They are also called EEPROMs (Electrically Erasable Read Only Memory) because they can be electrically erased then written on to (flashed) without having to take them out of the computer, and without using ultraviolet light.
Since RAM can be read faster than most ROMs, the frequently used content of the ROM is sometimes copied to RAM (shadowed)

23. Secondary Storage Magnetic disk Optical media
Hard disk (File, Directory, Folder)
Floppy disks
Zip disks
Optical media
CD (680 MB)
DVD (4.7 GB)
Magneto-optical disks (Pinnacle drives)
Magnetic tape (used primarily for long term archive)

24. Hard Disk Drive Basics

25. Input/Output Some Input Devices
Keyboard
Keypad
Mouse
Voice activation
Touch screen
Digitizers and pen-based (stylus) systems

26. Some Output Devices Monitor Printer Speakers
Communication (comm) ports
Modems (both input and output)
Network interface cards (both input and output)