Chapter 2
Main components of the computer
2.0 Introduction
The computer accepts input, processes it and produces an output. It is helped in these
tasks by a number of components.
A simplified diagrammatic representation of the process can be represented as
follows:
Backing
Store
Input
Main
Memory
Output
Processor
Figure 2-1: The computation process.
From this diagram, the different components of the computer can be classified in one
of the following groups:
 Processor,
 Main memory,
 Output devices,
 Input devices.
Each of these components exists in several forms.
In the simple microcomputer (see Figure 2-2) found in our home or in the computer
lab, the following components can be immediately identified:



Figure 2-2: A common desktop computer
The input devices: the keyboard and the mouse.
The output devices: the screen, the speakers and the printer.
The processor and main memory, which are found inside the system unit, and
hence hidden from us.
The microcomputer can also be seen as comprising the System Unit, the Video
Display Unit (VDU or screen), the Keyboard and mouse and the peripheral devices.
2.1. The System Unit
The System Unit is contained inside a casing known as the system cabinet. A close
look at it (see Figure 2-3) will show that it is composed of:
 A number of printed circuits boards,
 A number of distinct devices such as the different drives,
 A number of slots for additional cards,
 Some memory chips,
 A number of ports,
 Some bus connecting all these parts together.
Memory
Disk
Drives
Microprocessor
Ports
Cards
System
Board
Figure 2-3: Inside a system unit.
These printed circuit boards are known as cards and each of these cards has a specific
use inside the computer.
A list of some of the cards commonly found inside a common microcomputer is:
 The motherboard,
 The network card,
 The sound card.
2.1.1. The motherboard
The motherboard, also known as the system board, is the main component of the
system unit. It contains a number of electrical circuits and a number of slots (see
Figure 2-4) for the connection of all the other components. These components
comprise:
 The processor
 The Input/Output Devices e.g. Mouse, Keyboards etc…
 The different expansion cards mentioned before.
Figure 2-4: A motherboard.
The connection of these components can be done in a number of different ways.
Some devices e.g. the Keyboard, Video Display Unit etc. can be connected very easily
from the outside. Other components may require some technical knowledge. For
example, a Sound Card has to be connected in a slot found inside the System Unit. A
Network Card requires even more technical knowledge, as its settings have to be
adjusted for its proper functioning.
The main memory as well as the microprocessor has specific slots on the
motherboard. Their legs (see Figure 2-5) are connected to the appropriate circuits on
the motherboard and hence to the other devices for the proper functioning of the
computer.
Figure 2-5: A memory chip.
There are a number of different types of motherboards available on the market. These
differ mainly in terms of processor, amount of memory and cards they can accept.
Figure 2-6 shows two different motherboards where we can easily spot the different
layouts of components.
(a)
(b)
Figure 2-6: Two different motherboards
2.1.2. The processor
The processor, also known as a CPU or Central Processing Unit, is the heart of the
computer, whether it is a desktop machine, a server, or a laptop. All data are
processed in it.
When the processor is composed of only one chip, it is called a microprocessor.
There are a number of different types of processors available on the market nowadays.
The microprocessor may be a Pentium from Intel Corporation, a K6 from AMD, a
PowerPC, a Sparc or any of the many other brands and types of microprocessors, but
they all do approximately the same thing in approximately the same way.
These different microprocessors may vary in terms of price and performance. The
following table gives a comparison between the Intel Pentium III and the AMD K6 III.
Processor Features
Performance Benefits
AMD-K6®-III with 3DNow!™ technology
Pentium®III
Process Technology (micron)
0.25
0.25
Die size (mm2)
Smaller die size=lower cost
118
140
Clock speed (MHz)
Faster clock speed generally means faster processing and apps launching
400
450
450
500
Total System cache (max)
Larger cache typically improves overall performance
2368 KB
544 KB
*Internal cache
Built-in feature that helps the CPU access data and instructions even faster
320 KB
32 KB
L2 cache support
Augments L1 cache, making data and instruction access even faster
256 KB (full speed)
512 KB (half speed)
L3 cache support
Provides additional system cache improving overall performance
Yes
(up to 2 MB)
No
Processor bus (max bus speed)
Moves data between CPU and main memory
100MHz
100MHz
MMX™ Technology
Improves quality and performance of integer-based multimedia applications
Yes
Yes
Advanced Floating Point Multimedia Technology
Enables superior visual and multimedia experience
Yes
3DNow! Technology
Yes
Streaming SIMD Extensions
Accelerated Graphics Port Support
Speeds up 3D graphics
Yes
Yes
X86 compatibility
Standard industry architecture, essential for running standard PC applications
Yes
Yes
*AMD-K6-III internal cache includes 64 KB L1 cache and 256 KB full-speed on-chip L2 cache
Figure 2-7: Processor Comparison
The first microprocessor was the Intel 4004, introduced in 1971 to power one of the
first portable electronic calculators. All it could do was add and subtract four bits at a
time. Before the 4004, engineers built computers either from collections of chips or
from discrete components (that is, transistors wired one at a time).
The first microprocessor used in the home computer was the Intel 8080 which was a
complete 8-bit microprocessor introduced in 1974. The Intel 8088 was introduced in
1979 and incorporated into the IBM PC, which first appeared around 1982, and this
started the era of home computing.
The PC market moved from the Intel 8088 to the new Intel Pentium-III through the
80286, the 80386, the 80486, the Pentium and the Pentium-II. All of these are
improvements on the basic design of the 8088. For example, the new Pentiums-IIIs
can execute any piece of code that ran on the original 8088, but runs about 3,000
times faster.
The following table, compiled from The Intel Microprocessor Quick Reference Guide,
helps to understand the differences between the different processors that Intel has
introduced over the years.
Name
8080
8088
80286
Date Transistors
Microns
Clock speed Data width
MIPS
1974 6,000
6
2 MHz
8
0.64 MIPS
1979 29,000
3
5 MHz
16 bits,
0.33 MIPS
8 bit bus
1982 134,000
1.5
6 MHz
16 bits
1 MIPS
80386
1985
275,000
1.5
16 MHz
32 bits
5 MIPS
80486
Pentium
1989
1993
1,200,000
3,100,000
1
0.8
25 MHz
60 MHz
20 MIPS
100 MIPS
Pentium II
1997
7,500,000
0.35
233 MHz
Pentium III
1999
9,500,000
0.25
450 MHz
32 bits
32 bits,
64 bit bus
32 bits,
64 bit bus
32 bits,
64 bit bus
400 MIPS?
1,000 MIPS?
First home computers
First IBM PC
IBM ATs. Up to 2.66 MIPS at
12 MHz
Eventually 33 MHz, 11.4
MIPS
Eventually 50 MHz, 41 MIPS
Eventually 200 MHz
Eventually
MIPS?
450
MHz,
800
Figure 2-8: Intel microprocessors
Information about this table:






The date is the year that the processor was first introduced. Many processors
are re-introduced at higher clock speeds for many years after the original
release date.
Transistors is the number of transistors on the chip. It can be seen that the
number of transistors on a single chip has risen steadily over the years.
Microns is the width, in microns, of the smallest wire on the chip. For
comparison, a human hair is 100 microns thick. As the feature size on the chip
goes down, the number of transistors rises.
Clock speed is the maximum rate that the chip can be clocked.
Data Width is the width of the ALU.
MIPS stands for Millions of Instructions Per Second, and is a rough measure
of the performance of a CPU. Modern CPUs can do so many different things
that MIPS ratings lose a lot of their meaning, but a general sense of the relative
power of the CPUs from this column can be deduced.
2.1.2.1. The Chip
A chip is also called an integrated circuit. Generally it is a small, thin piece of
silicon onto which the transistors have been etched. A chip might be as large as an
inch on a side and can contain as many as 10 million transistors. Simple processors
might consist of a few thousand transistors etched onto a chip just a few millimetres
square.
Figure 2-9: The Pentium II chip
2.1.2.2. Inside a Microprocessor
The main components of the microprocessor are the Arithmetic and Logic Unit (ALU)
and the Control Unit (CU). The CU directs electronic signals between the memory
and the ALU as well as between the CPU and I/O devices. The ALU performs
arithmetic and comparison operations.
A microprocessor executes machine instructions that tell it what to do. Based on the
instructions, a microprocessor does three basic things:



The ALU (Arithmetic/Logic Unit) can perform mathematical operations like
addition, subtraction, multiplication and division.
It can move data from one memory location to another
It can make decisions and jump to a new set of instructions based on those
decisions.
All the sophisticated things a microprocessor does can be decomposed in terms of
these three basic activities.
2.1.2.3. Microprocessor Instructions
Even a simple microprocessor has a quite large set of instructions that it can perform.
The collection of instructions is implemented as bit patterns, known as opcodes, each
of which has a different meaning when loaded into the instruction register. Since
humans are not good at remembering bit patterns, a set of short words or mnemonics,
is defined to represent the different bit patterns. This collection of words is called the
assembly language of the processor. An assembler can translate the words into their
bit patterns very easily, and then the output of the assembler is placed in memory for
the microprocessor to execute.
The instruction decoder needs to turn each of the opcodes into a set of signals that
drive the different components inside the microprocessor. Consider the ADD
instruction as an example:



During the first clock cycle the instruction is loaded.
During the second clock cycle the ADD instruction is decoded.
During the third clock cycle, the program counter is incremented and the
instruction executed.
This is known as the Fetch-Execute cycle of the microprocessor. Every instruction
can be broken down as a set of sequenced operations like the above. Some
instructions take 2 or 3 clock cycles while others take 5 or 6 clock cycles.
2.1.2.4. Trends in Microprocessor Design
The number of transistors available has a huge effect on the performance of a
processor
More transistors also allow a technology called pipelining. In a pipelined architecture,
instruction execution overlaps. So even though it takes 5 clock cycles to execute each
instruction, there can be 5 instructions in various stages of execution simultaneously.
So it seems that one instruction completes every clock cycle.
Many modern processors have multiple instruction decoders, each with its own
pipeline. This allows multiple instruction streams, which means that more than one
instruction can be completed during each clock cycle. This technique can be quite
complex to implement, so it takes lots of transistors.
The trend in processor design has been toward full 32-bit ALUs with fast floating
point processors built in and pipelined execution with multiple instruction streams.
There has also been a tendency toward special instructions (like the MMX instructions
designed for Multimedia purposes) that make certain operations particularly efficient.
There has also been the addition of hardware virtual memory support and L1 caching
on the processor chip. All of these trends push up the transistor count, leading to the
multi-million transistor microprocessors available today and these processors can
execute about one billion instructions per second.
2.1.2.5. Data representation
Inside the computer, data are represented using the binary system. This system or base
consists of only two digits: 0 and 1. In the computer these digits are represented by the
states of electrical circuits: a low state stands for 0 and a high state for 1. One binary
digit is known as a bit and 8 bits make a byte.
Any character can be represented by a combination of binary digits. A byte can
represent up to 256 different characters.
Memory capacity is expressed in terms of Megabytes (or MB). One MB is 220 Bytes
and is roughly equal to 1 million Bytes. The RAM of a computer is expressed in terms
of MB nowadays.
The Kilobyte (or KB) is 210 Bytes or roughly 1 000 Bytes. The cache of a computer is
expressed in terms of KB.
The Gigabyte (GB) is 230 Bytes. It is used to express Hard Disk capacity.
The examples used are just to give an idea of the capacity of the different mediums in
a computer. We can express the size of any storage device in terms of any unit.
There are a number of different binary systems:
ASCII: The American Standard Code for Information Interchange is the main system
used in microcomputers.
EBCDIC: The Extended Binary Coded Decimal Interchange Code was developed by
IBM and is used in large computers.
Unicode: This is a sixteen-bit code. It can represent up to 2 16 different characters. It
can support languages such as Chinese and Japanese, which have a very large set of
characters.
The electrical signal corresponding to a character is generated when the corresponding
key is pressed on the keyboard. Since there can be noise on the lines from the
keyboard to the processor, the signal can be corrupted. So a ninth bit, the parity bit, is
added before transmission to detect errors. There are two types of parity bit:

Even parity bit: The bit is added in such a way that the total number of 1 in the
signal is even. Any error is detected at reception, and in case of error, the
signal has to be sent again.

Odd parity bit: The total number of 1 has to be odd.
2.1.3 Memory
The computer contains a number of different types of memory each for a specific use.
The different types of memory commonly found inside the computer are the RAM,
ROM and CMOS. These are made up of high-speed access electronic circuits and can
store data under certain conditions.
The address and data buses, as well as the RD and WR lines of the microprocessor
connect to the memory chips. In the sample microprocessor considered earlier, the
address bus is 8 bits wide and the data bus 8 bits wide. This means that the
microprocessor can address 28 = 256 bytes of memory, and it can read or write 8 bits
of the memory at a time.
All memory cells have a specified address and no two cells can have the same
address. For example, it can have 128 bytes of ROM starting at address 0 and 128
bytes of RAM starting at address 128.
2.1.3.1. ROM
ROM stands for Read-Only Memory. A ROM chip is programmed with a permanent
collection of pre-set bytes.
On a PC, the ROM contains essential information for the start-up of the computer
such as the BIOS (Basic Input/Output System). When the microprocessor starts, it
begins executing instructions it finds in the BIOS. The BIOS instructions test the
hardware in the machine, and then it goes to the hard disk to fetch the boot sector.
This boot sector is another small program containing some essential instructions to
start the computer, and the BIOS stores it in RAM after reading it off the disk. The
microprocessor then begins executing the boot sector's instructions from RAM. The
boot sector program tells the microprocessor to fetch some other program from the
hard disk into RAM, executes it, and proceeds in the same way until the entire
operating system is loaded and executed. This process is explained in more details in
Chapter 7 which deals with Systems Software
Nearly all computers contain some amount of ROM. While it is possible to create a
simple computer that contains no RAM, for example microcontrollers with some
RAM bytes on the processor chip itself, it is generally impossible to create one that
contains no ROM.
There are some other types of ROM on the market, namely:
PROM: Programmable ROM, which can be written only once using special
equipment.
EPROM: Erasable PROM, which can be erased using Ultra Violet light and used
again. There are also some electrically erasable chips known as EEPROM.
2.1.3.2. RAM
RAM stands for Random Access Memory. RAM contains bytes of information and
the microprocessor can read or write to those bytes depending on whether the Read or
Write signal is on. RAM chips lose their content once the power goes off. When
talking of the memory of a computer we usually refer to its main memory or RAM.
The typical RAM content of a microcomputer nowadays is 64 MB. The RAM is the
working memory of the computer and it stores the user programs and data. There are
two main types of RAM: Static and Dynamic RAM.
Dynamic random access memory (DRAM) is the most common kind of RAM for
personal computers and workstations. DRAM is dynamic in that, unlike static RAM,
it needs to have its storage cells refreshed or given a new electronic charge every few
milliseconds.
Static RAM does not need refreshing because it operates on the principle of moving
current that is switched in one of two directions rather than a storage cell that holds a
charge in place. Static RAM is generally used for cache memory, which can be
accessed more quickly than DRAM.
DRAM stores each bit in a storage cell consisting of a capacitor and a transistor.
Capacitors tend to lose their charge rather quickly; thus, the need for recharging.
2.1.3.3. CMOS
CMOS or Complementary Metal Oxide Semiconductor memory is used to store the
set up configuration of a computer. It is a Read and Write memory but its composition
is different from the RAM since it does not lose its information when its power supply
is cut off. CMOS is very expensive compared to RAM. It uses a battery to keep its
information. So when the battery gets low, the CMOS loses its information. This is
noticed when the computer loses its configuration and gives an error when turned on.
2.1.3.4. New types of memory
Some newer types of memory are being developed. These memory chips are able to
keep their information when the power supply is cut off. In this case they give a
protection against power failure. But their price is an important factor affecting their
use in a computer.
2.1.3.5. Cache memory
Caching is a technology based on the memory subsystem of the computer. The main
purpose of a cache is to increase the speed of the computer while keeping the price of
the computer low. Caching appears on every computer in a variety of forms. There are
memory caches, hardware and software disk caches, page caches, etc. Virtual memory
is even a form of caching.
Some important facts about caching:




Cache technology is the use of a faster but smaller memory type to accelerate a
slower but larger memory type.
When using a cache, it must be checked to see if the item is in it. If the item is
in the cache, we have a cache hit and if not, we have a cache miss and the
computer must fetch the item from the larger, slower memory area.
A cache has some maximum size that is much smaller that the larger storage
area.
It is possible to have multiple layers of cache. This would be a 2-level cache.
Modern computers have both L1 and L2 caches.
When the microprocessor accesses the main memory (RAM), it does so in an access
time of around 60 nanoseconds. This is much slower than the typical microprocessor,
which can have cycle times as short as 2 nanoseconds. We can also have a small
memory bank with an access time of around 30 nanoseconds between the
microprocessor and the RAM. The access time is hence twice faster than the main
memory access. This is known as a level 2 cache or a L2 cache. We can build a
smaller but faster memory system directly into the microprocessor's chip itself. This
memory will be accessed at the speed of the microprocessor and not the speed of the
memory bus. This is a L1 cache, which on a 233 MHz Pentium is 3.5 times faster than
the L2 cache, which is 2 times faster than the access to main memory.
There are a lot of subsystems in a computer; and a cache can be used between many of
them to improve performance. Hence:

We have the microprocessor, which is the fastest thing in the computer.

Then there is the L1 cache caching the L2 cache. We have memory accesses at
full microprocessor speed (< 10 ns, 4KB to 16KB in size usually)

The L2 cache caches the main memory. We have memory access of type Static
Random Access Memory (SRAM) (around 20 - 30 ns, 128KB to 512KB in
size)

The main memory is used as a cache for even slower peripherals like hard
disks and CD-ROMs. We have memory access of type Random Access
Memory (RAM) (around 60 ns, 32MB to 128MB in size)

The hard disks are used to cache an even slower medium for example, the
Internet connection. They are mechanical and slow (access time of around 12
milliseconds, 1GB to 10GB in size). The Internet is incredibly slow (between
1 sec. and 3 days) but has unlimited size.
The Internet connection is the slowest link in the computer. So the browser (Internet
Explorer, Netscape, etc.) uses the hard disk to store HTML pages into a special folder.
The first time an HTML page is requested, the browser fetches it and a copy is also
stored on the disk. When this page is next requested, the browser checks if the date of
the file on the Internet is newer than the one cached. If the date is the same, the
browser uses the one on the hard disk instead of downloading it from Internet. In this
case the smaller but faster memory system is the hard disk and the larger and slower
one is Internet.
Cache can also be built directly on peripherals. Modern hard disks come with some
fast memory (around 512K) hardwired to the hard disk. The computer does not
directly use this memory, but the hard disk controller does. For the computer, these
memory chips are the disk itself. When the computer asks for data from the hard disk,
the hard disk controller checks into this memory before moving the mechanical parts
of the hard disk, which is very slow compared to memory. If it finds the data the
computer asked for in the cache, it will return the data stored in the cache without
actually accessing data on the disk itself, thus saving a lot of time.
2.1.4. Slots for extension cards
The motherboard contains a number of slots to add extension cards (see Figure 2-10
for an example) to the computer. These cards, also known as expansion boards,
extend the possibilities of the computer.
Figure 2-10: An extension card
These slots exist as computer manufacturers have recognised the growing need for
additional features in the computer.
The possibility of a computer can be expanded since microcomputers have an open
architecture and hence users can add new devices easily. The open architecture has
been designed by a consensus among manufacturers.
However, new devices cannot be added easily in computers having a closed
architecture.
The slots may have different width but the trend is for 64-bit width just as the system
bus of the computer.
The functions of some very commonly used cards tend to be integrated in the
motherboard. For example some motherboards come with an integrated Sound Card
as well as a TV card.
Some examples of expansion card are:
Video Card: All computers require a video card. The card usually contains memory
(RAM) that is reserved for the video (monitor) display. For monitor displays at high
color and resolution, 2 or more megabytes of RAM are required. Video cards can vary
greatly in quality (as can sound cards) so it pays to study the specifications before
buying a new computer.
Network card: This card allows the connection of the computer to a network and deals
with all network communications.
SCSI card: Small computer system Interface cards use only one slot to connect several
devices to the system unit.
PC card: It is a small credit card sized card which is used in portable computers. PC
cards have a number of purposes and are also known as PCMCIA (Personal Computer
Memory Card International Association) cards. These cards are inserted and replaced
outside the computer.
A feature commonly associated with these cards is plug and play. It is a set of
hardware and software standard to create devices that can configure themselves. The
complex task of setting the configuration of these devices is thus eliminated. On startup, the computer is going to recognise and automatically configure any device added
to it.
2.1.5. Ports
Ports are connection sockets found outside the system unit at the back, in contrast to
expansion slots found inside it. They are used for the connection of external devices.
An example of a port is the printer port used to connect the printer.
The port may be found on the system board itself or on an expansion board. Hence the
printer port is on the motherboard while the speakers are usually connected to a port
on the sound card.
Ports may be parallel or serial.
Parallel ports are used to connect devices over a short distance. Eight bits of data are
transmitted in parallel. Apart from wires to carry the data, there are also some control
lines. An example of a parallel port is the printer port.
Serial ports send data one bit at a time. Some examples are the mouse, keyboard and
modem ports.
2.1.6. Drives, The Storage Devices.
Programs and data must be stored somewhere if they are to be used more than once.
Hard disks, Floppy disks and CD ROMs are the most common forms of permanent
storage devices. These devices act as both an input and output device. They are also
used to transfer files from one workplace to another.
A computer usually contains a number of drives and it is common to see one CD
drive, one floppy disk drive and at least one Hard Disk in a computer.
An important aspect to consider when choosing a data storage device is the Disk
Access Time. This is the interval between the moment the command to transfer the
data is given and the time the transfer is complete. Disk access times depend on the
seek time and data transfer rate.
Some newer types of drives have appeared in computers recently. Thus we find Zip
drives which can be compared to Floppy disks of 100 MB or even higher and CDWriters.
Storage devices are discussed in more details in Chapter 5.
2.1.7. Bus
The bus, or bus line, connects the different parts of the system unit to each other as
well as the components of the CPU to each other.
The bus is a path for bits to travel and its width is an indication of the speed of a
computer. The bus width currently used is 64 bits meaning that 64 bits can travel in
parallel.
There is a number of bus architecture on the market nowadays:
ISA: The Industry Standard Architecture is currently 32 bits wide and was developed
by IBM.
MCA: The Micro Channel Architecture was developed by IBM for the 386 and is
currently 64 bits wide.
EISA: The Extended ISA is now 64 bits wide and was proposed by a consortium of
nine computer manufacturers led by Compaq Computer Corp.
PCI: The Peripheral Component Interconnect is a high-speed 64 bits bus, much faster
than EISA and MCA buses. It is the most recently developed type.
The width of the address bus on the other hand is a measure of how much memory the
computer can address. The Intel Pentium III has an address bus of 64 bits and can
hence address 264 bytes of memory.
2.1.8. System clock
This component is found on the motherboard. All devices in the computer, including
the microprocessor are sequenced by its speed. The faster the clock, the faster the
computer can execute instructions. Its speed is expressed in terms of Megahertz
(MHz). Current computers have a system clock running at 450 MHz.
2.2. Input and Output Devices
These devices are found outside the system cabinet and are sometimes referred to as
peripherals. They are meant to simplify our interaction with the computer and thus
provide a means of communication between the computer and its human operator.
Computers come with a number of Input and Output devices.
The most common visible input devices are the Keyboard, the mouse and the scanner,
while the most common output devices are the printer and the Video Display Unit.
Peripheral devices are discussed in more details in Chapter 4.
2.3. Other types of computers
Apart from the Personal computer used as main example in this chapter, there are
some other types of computers we may come across.
The sun Workstation is similar to a PC at first sight. But it uses a much more powerful
processor such as the Sparc. It is mainly used for high end computing.
Mini-computers and mainframes have several terminals attached to them, as they are
multi-user systems. The trend is to put them in a network to allow more users to
access them, just as for a Workstation.
Embedded systems refer to dedicated systems built around a processor. An example is
the Automatic Teller Machine (ATM) of banks. They have only one purpose and their
Input/Output devices limit our interaction with them.
There are also some multiprocessor machines used in computing extensive
environments. These computers have several processors to process information at a
higher rate.
Another concept gaining momentum is clustering. A cluster is a group of terminals or
workstations attached to a common control unit (or server) or a group of several
servers that share work and may be able to back each other up if one server fails. As
of mid-1997, a two-server Windows NT cluster in which each system could back up
the other in case of failure was priced at about $23,000. The cost of writing failure
scripts, considered to be a sophisticated programming task, would be extra. The
cluster is a cheap alternative to expensive mainframes.
References:
Advanced Micro Devices Inc Web Site: http://www.amd.com
ePanorama - microprocessor and microcontroller pages: http://www.usepanorama.net
Information and Communications Technology Companion:
http://www.painsley.org.uk/ictcompanion/
Intel Corporation Web Site: http://www.intel.com
O’LEARY Timothy J. , O’LEARY Linda I., Computing Essentials, Irwin Mc
Graw - Hill
ROSENTHAL Morris, Online Illustrated Step-by-Step Guide to Building a New ATX
PC Copyright 2000 by http://www.daileyint.com/
The Intel Microprocessor Quick Reference Guide, Intel Corporation
Whatis.com Web Site: http://www.whatis.com
Further Reading
GAONKAR R. S., Microprocessor architecture, programming, and applications,
New age International Limited, Publishers
HALL D. V., Microprocessors and Interfacing, Glencoe Macmillan/ Mc Graw – Hill
HAMACHER V. C., VRANESIC Z. G., ZAKY S. G., Computer Organization, Mc
Graw - Hill