The document discusses the key components of computer hardware. It describes the differences between hardware and software, with hardware being the physical parts that can be touched, and software being the logical instructions. The main components of a computer system are then outlined as the input, output, memory, CPU, and secondary storage units. Several types of computers are also defined based on size, including microcomputers, mainframes, supercomputers, mini computers, and embedded systems. Common examples are provided for each type along with their typical uses. Memory and storage technologies like RAM, ROM, cache, hard disks, optical disks, and USB drives are further explained.

1. Computer Hardware
A level Computing Book (Reference)
By
P.M .Heathcore
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2. Computer System
• Hardware
• Software
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3. Differences
Hardware
• Physical Component of a
Computer
• We can touch these parts
• Allow user to enter data and
information into computer and
retrieve
• Can not perform any task
without Software
• If problem occur in hardware
then it will repaired.
Software
• Logical Component of a
Computer
• We can not touch
• These are in form of instructions
that tell the computer what that
to do
• It can not executed without
hardware.
• If any problem in software then
it will reinstall.
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4. Computer Components
• Logical units of a computer
• Input unit
• Output unit
• Memory unit ( Main Memory )
• Central processing unit (CPU)
• Secondary storage unit
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5. Computer Component
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Input Unit
CPU
Unit
Ram / Rom
ALU & Logical
Unit
Control Unit
Output Unit
Storage Devices

6. Types of computers by Size
• Micro computers
• Mainframe Computers
• Super Computers
• Mini Computers
• Embedded Computers
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7. Micro Computers
• Are the computers that you are most likely to encounter
at home or in school and colleges.
• It consist of one or more input device ,output device,
memory and processor.
Examples
• PCs
• Apples
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8. Types of Micro Computers
• Desktop Computers
• Laptop and notebook Computers
• Personal Digital Assistants (PDA)
• Palmtop Computers
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9. Mainframe computers
• Thousands of terminals attached to it.
• Larger mainframe computers carry out 250 million
instructions per second.
• It Consist of multiple processors.
• Used large organizations such as banks, insurance
companies, airlines and government department.
• Disadvantage:
• Due to immense power they produce large amount
of heat so its require air conditioned.
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10. Examples
• IBM43810
• NEC610
• DEC 10 etc
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11. Supercomputers
• Largest category of computer, costing millions of
pounds.
• It is complex ,large storage and advanced computers.
• They are mostly used by scientific and industrial
research departments.
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12. Uses
• NASA
• Weather centre
• Stock Exchange
• Weapon design
• Mapping the surface of planets.
• Studying the neural network of brain
• Preparing models of chemical systems.
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13. Examples
• CRAY-XP
• ETA-10
• Blue sky
• ASCI White
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14. Mini computers
• Have a size , power and cost somewhere between
those of microcomputers and mainframes.
• It is much powerful then some of the mainframes
still in use.
• It is used by business institutes and departments.
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15. Examples
• Vax-8800
• MV-1500
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16. Embedded Computers or
Microprocessors• Is a single chip that perform the functions of a
central processing unit
• Many microprocessors makes are Microcontrollers
also called embedded.
• Embedded computers serve as the brain of a larger
piece of machine.
• Their software is stored in the computer’s own.
• They serve as a personal computer but not have a
monitor, keyboard and mouse
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17. Uses
• Microwaves programmable ovens
• Blood pressure monitors
• Air bag sensors
• Washing machines
• Video recorders
• Alarms
• Digital cameras
• MP3 players
• Car engine Controllers
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18. Processors
• Most computer use Ics.
• It hold millions of electronic components such
as transistors
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19. Functions
• It controls the transmission of data from input
device to memory
• It processes the data held in main memory
• It controls the transmission of information from
main memory to output device.
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20. Main Memory
• Instructions and data are held in main memory which
is divided into millions of addressable storage units
called bytes.
• One byte can hold one character
• Total bytes in main memory referred to as the
computer’s memory size.
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21. Memory Sizes measurement
• I nibble = 4 bits
• I byte = 8 bits
• I kilobytes (kb) = 1024 bytes
• 1 Megabytes (Mb) = 1024kilobytes
• 1 gigabytes (Gb) = 1024Megabytes
• 1 terabytes (TB) = 1024Gigabytes
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22. Types of Main Memory
• Ram (Random Access Memory)
• Rom (Read Only Memory)
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23. RAM & ROM
Ram
• Its temporary memory
• Read and Write data
• Data can be changed or
deleted
• It is a Volatile memory
• The instructions written in
Ram at the time of execution
Rom
• Its Permanent memory
• It can only be read
• Data can not change or deleted
• It is non Volatile
• The instructions are written into
Rom at manufacturing time.
(BIOS)
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24. Cache Memory
• A Cache is a small and very fast memory
• To speed up the transfer of data and
instructions.
• It is located inside or close to the CPU Chip.
• It is faster than Ram
• The data and instructions that are most recently
or most frequently used by CPU are stored in
cache.
• The amount of cache memory is generally
between 1kb and 512kb
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25. How Cache memory Works
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Processor
Cache Memory
Main Memory
Single Word of data Transferred
Block of data transferred

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CPU
Memory
(main store)
Cache
controller
Cache
memory
Typically
4MB
Typically
64 KB
HitMiss

27. Disk Storage
• The most common form of auxiliary
storage ( External or secondary or
backing store) is disk
• Magnetic media
• Hard disk
• Tape
• Floppy disk
• Optical storage device
• CD
• DVD
• CD-R
• CD-RW
• CD-ROM
• USB Drive
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