Computer Introduction-Lecture02 for applied scince college students, Seiyun University , yemen 2023-2024 Academic year. لطلاب كلية العلوم التطبيقية بجامعة سيئون مقدمة في علوم الحاسوب المحاضرة الثانية

1. Lecture No. 2: Computer hardware
Lecturer: Dr. Mazin Alkathiri
Department of Computer Science,
Faculty of Applied Science,
Seiyun University
2023

2. Components Of A Computer ?
Computer divided to two main parts:
‫الماديات‬
(
Hardware
)
1- ‫البرمجيات‬
(
Software
)
2-
‫الماديــــات‬
Hardware:
The term hardware refers to the physical components of
your computer such as, the electronic & Metallic parts
electric cables …etc.
1. Input Unit Devices .
2. Processing Unit.
3. Output Unit.

4. Input devices The input unit is responsible for taking input
and converting it into computer understandable form (the
binary code).
Different input devices are used for different types of input.
Some of the input devices are as under –
 Mouse
 Keyboard
 Microphone
 Joy-stick
 OMR
 MICR
 Light Pen
 Scanner
 Camera

5. The CPU is called the brain of the computer because it controls the
entire computing system. As the CPU is located on a small chip, it is
also called the microprocessor.
In the CPU, there are three primary components.
 Arithmetic and Logic Unit (ALU): The ALU, as its name suggests
performs mathematical calculations and takes logical decisions.
 Control Unit: The Control unit coordinates and controls the data
flow in and out of CPU and also controls all the operations of ALU,
memory registers and also input/output units.
 Memory Registers: A register is a temporary unit of memory in the
CPU to temporarily hold some data during processing.

6. Example of some CPUs by Intel.
• 8088 1985
• 80386 1987
• 80486 1988
• Pentium – I 1990
• Pentium – II 1994
• Pentium - III 1995
• Pentium – IV 2001
• Core 2 Duo 2006
• Core i7 2008

7. Output devices The output coming from CPU is in the
form of electronic binary signals which needs to be
converted again to human understandable form.
.i.e. either textual or graphical or audio visual form. It is
the responsibility of an Output unit to produce output
after processing.
Different output devices are used for different types of
output. Some of the output devices are
Monitor(most common form of output .The screen on
monitor is made up of thousands of tiny coloured dots
called pixel)
Projector
Printer
Plotter
Speaker
Headphone

8. Computer memory is the storage space in the computer,
where data is to be processed and instructions required for
processing are stored. The memory is divided into large
number of small parts called cells. Each location or cell has
a unique address.
Memory is primarily of three types :−
Cache Memory
Primary Memory/Main Memory
Secondary Memory

9. is a very high speed semiconductor memory which can
speed up the CPU. It acts as a buffer between the CPU and the
main memory. It is used to hold those parts of data and
program which are most frequently used by the CPU.
 Advantages
1. Cache memory is faster than main memory.
2. It consumes less access time as compared to main memory.
3. It stores the program that can be executed within a short
period of time.
4. It stores data for temporary use.
 Disadvantages
1. Cache memory has limited capacity.
2. It is very expensive.

10. Main Memory is often known as Primary memory.
 It is not like human memory because data stored
in this memory, automatically flushes out with
power cut off and can not be recovered later. Every
memory location has a definite address.
Characteristics of Main Memory
These are semiconductor memories.
Usually volatile memory.
It is the working memory of the computer.
Faster than secondary memories.
A computer cannot run without the primary
memory.

11. Secondary Memory is also known as external
memory or non-volatile memory.
 CPU directly does not access these memories, instead
they are accessed via input-output routines. The
contents of secondary memories are first transferred
to the main memory, and then the CPU can access it.
 Examples are, disk, CD-ROM, DVD, etc.
Characteristics of Secondary Memory
These are magnetic and optical memories.
It is known as the backup memory.
It is a non-volatile memory.
Data is permanently stored even if power is switched off.
It is used for storage of data in a computer permanently.
Computer may run without the secondary memory.
Slower than primary memories.

12. The smallest unit is bit, which mean either 0 or 1.
1 bit = 0 or 1
1 Byte = 8 bit
1 Kilo Byte = 1024 Byte= 210 Byte
1 Mega Byte = 1024 KB= 210 KB
1 Gega Byte = 1024 MB= 210 MB
1 Tera Byte = 1024 GB= 210 GB
1 Peta Byte =1024 TB= 210 TB
1 Exa Byte =1024 PB= 210 PB
1 Zetta Byte = 1024 EB= 210 EB
1 Yotta Byte = 1024 ZB= 210 ZB

13. Main Memory or primary memory is divided into two types-
 RAM (Random Access Memory)
 ROM (Read Only Memory)
RAM : Random Access Memory. It is the main memory of the computer.
It is volatile memory, which means the information gets erased whenever
the power supply is switched off.
There are different types of RAM:
◦ Static RAM (SRAM) is very fast but much more expensive than DRAM.
SRAM is often used as cache memory due to its speed.
◦ Dynamic RAM (DRAM) is used for most system memory because it is
cheap and small.

14. ROM : Read Only Memory
Information is burnt into the ROM chip at the time of
manufacturing. It can not be erased or altered and fresh
information can not be written into the ROM. The BIOS is
stored on ROM because the user cannot disrupt the
information.
 BIOS : Basic Input Output System. It contains some
instructions required internally by the computer.

15.  A secondary storage device refers to any non volatile
storage device that is internal or external to the computer.
which enables permanent data storage.
 Because Primary memory has its own limitations, secondary
storage or storage unit is very much required.
 It is used to store large amount of data.
Examples:
 Hard disk (Internal/External)
 Pen drive
 CD
 DVD
 Blue Ray Disks
 Memory Cards
 Magnetic Tapes

16.  A punched card, punch card, IBM card, or
Hollerith card is a piece of stiff paper that
contains digital information represented by
the presence or absence of holes in
predefined positions.

17. ©2001 Paradigm Publishing Inc. 17
Hard Disk Storage
Sealed Metal Housing
The housing protects the internal
components from dust particles that could
block the gap between the read/write heads
and the platters, causing the hard drive to
crash.
Drive Spindle
The drive spindle is connected to a
motor which spins one or more
magnetically coated platters at several
thousand revolutions per minute. More
platters mean greater disk storage
capacity.
Head Actuator
This component moves the
collection of read/write heads
across the surface of the platters
with extreme accuracy. It aligns
the heads with the tracks that
lie in concentric circles
on the platters.
Read/Write Head
These read/write heads move in
unison across the surfaces of the
platters. The heads write data to
the platters by aligning magnetic
particles on the surface and read
data by detecting the polarity of
the particles.
Sector
When formatting the hard drive, the
computer divides the disk into radial
sections called sectors.
Track
Circular and concentric paths
the read/write heads follow
when reading information from
the disk.

18. FLOPPY DISK :
 It is external to a computer and can be put into a
floppy disk drive (FDD) attached to a computer for
reading and writing information.
 It also uses electro magnetic theory to store
information. .
Standard capacity : 1.44 MB
Types:
1. 5¼ inch >> 1.25MB
2. 3½ inch >>1.44MB

19. These types of storage devices are mainly
used to back up small amounts of data and to
hold software, music an movies.
 Examples are CDs, DVDs and Blue-ray disks.
◦ ADVANTAGE – Small and portable.
◦ DISADVANTAGE – Very easily damaged due to their
fragility.
◦ ADVANTAGE – Cannot be overwritten accidentally
as they are read only once written to.
◦ DISADVANTAGE – Cannot store large amounts of
data (Max 50gb on Dual layer Blue-ray disks).

20.  These types of storage devices are small memory
sticks that use flash technology.
 They have a USB connector so they can be
connected to a variety of devices through a USB
port.
◦ ADVANTAGE – Small and portable.
◦ DISADVANTAGE – Restricted storage capacity compared
to HDDs and SSDs.
◦ ADVANTAGE – A very compatible storage device as most
desktop computers and laptop computers have USB
ports.
◦ DISADVANTAGE – Can only be written to a number of
times before they stop working.

21.  These types of storage devices are small
memory cards that use flash technology.
 They are often used for storage in digital
cameras and smart phones as extra memory.
◦ ADVANTAGE – Small and portable.
◦ DISADVANTAGE – Restricted storage capacity ( usually
64 – 128gb).
◦ ADVANTAGE – Data can be transferred between
devices if they have SD card readers.
◦ DISADVANTAGE – Small so could easily be lost.

22. These types of storage devices are mainly
used by large businesses to backup large
amounts of data.
◦ ADVANTAGE – Huge storage capacity.
◦ DISADVANTAGE – Special equipment is needed to
read and write the data.
◦ ADVANTAGE – Works out very cheap when
compared to other storage devices on a per-byte
basis.
◦ DISADVANTAGE – Slow data access as it is
accessed sequentially.

23. Major Components of a Motherboard
SIMM RAM Bank
Single Inline Memory Module
stores data to be used by the
microprocessor.
ROM BIOS
Basic Input/Output System
stores permanent instructions
that start the computer.
Power Connector
Supplies power to the
motherboard.
16 Bit ISA Slots
Allows expansion of computer
through modem, sound and
video cards.
32 Bit PCI Slots
Allows expansion cards that
can transfer data faster than
ISA slots.
Battery
Provides power
for the system
clock.
Cache RAM
Stores and retrieves information
for the microprocessor at a faster
rate than SIMM RAM so
instructions can be executed faster.
Microprocessor
Single integrated circuit that
executes the majority
of the instructions
to process
data.

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26. External Modem
Plugs into computer externally
Internal Modem
Fits inside computer
 Modems can send data from one computer to another using telephone lines.
 Modems are used in almost every aspect of work.
◦ Businesses use them to transfer files, data, and money.
◦ They are also used for teleconferencing, which allows people in various
locations to communicate over vast distances; these are sometimes called virtual
meetings.
◦ Schools use them to provide access to the Internet.
Modems