2. Outline
1. Introduction to Computer and Computing
2. Input and Output Devices and their Utilization
3. Storage Devices
4. Computer Networks
5. Computer Software
6. The System Life Cycle
7. Revision
8. Midterm
4. What is Computer?
A computer is an
electronic device that
accepts raw data,
processes it according to a
set of instructions and
required to produce the
desired result.
5. Operation
The operation of every computer can be divided
into four basic functions.
• Input: Information you put into the computer by way of keyboard, mouse etc.
• Processing :Also known as the "Brain" of the computer. Processes the information you put in
into human readable form.
• Output: The information you put into the computer is seen on the monitor screen and can be
printers out on paper and is readable.
• Storage: Either the computers memory, CD's, DVD's, Floppy Disc's, USB Flash Drives, etc.
6.
7. History Of Computers
• Before the 1500s, in Europe, calculations were made with
an abacus
• Invented around 500BC, available in many cultures (China,
Mesopotamia, Japan, Greece, Rome, etc.)
• In 1642, Blaise Pascal (French mathematician, physicist,
philosopher) invented a mechanical calculator called the
Pascaline
• In 1671, Gottfried von Leibniz (German mathematician,
philosopher) extended the Pascaline to do multiplications,
divisions, square roots: the Stepped Reckoner
• None of these machines had memory, and they required
human intervention at each step
8. • In 1822 Charles Babbage (English
mathematician, philosopher), sometimes called
the “father of computing” built the Difference
Engine
• Machine designed to automate the computation
(tabulation) of polynomial functions (which are
known to be good approximations of many
useful functions)
– Based on the “method of finite difference”
– Implements some storage
• In 1833 Babbage designed the Analytical Engine,
but he died before he could build it
– It was built after his death, powered by steam
10. Hardware Components
• The term hardware refers to the physical
components of your computer such as the system unit, mouse,
keyboard, monitor etc.
Simply We Can say
oInput Devices
oOutput Devices
oStorage Devices
oRAM
oROM
11. Software Components
The software is the instructions that makes the computer work.
Software is held either on your computers hard disk, CD-ROM, DVD
or on a diskette (floppy disk) and is loaded (i.e. copied) from the
disk into the computers RAM (Random Access Memory), as and
when required.
12. Input Devices "How to tell it what to do“
A keyboard and mouse are the standard way to interact
with the computer. Other devices include
Tracker Ball Touch Pads
Joystick Scanner
scanner
13. Output Devices "How it shows you what it is doing"
The monitor (the screen) is how the computer sends information back
to you. Other Devices includes Printers, LCD Screens, Plotters s,
Speakers.
Plotter
14. Storage Devices "How it saves data and
programs“
Hard disk drives are an internal, higher capacity drive which
also stores the operating system which runs when you
power on the computer.
15. RAM
• Hardware Device located on Motherboard.
• External Memory of CPU.
• Read Write Memory
• Volatile Memory
• Randomly Accessed
• Computer performance depends on
storage capacity of RAM
16. RAM
• RAM stands for Random Access Memory.
• It is the part of main memory where data and program instructions
are held while being manipulated or executed [44].
• It is also known as Read and Write Memory.
• It is a volatile (temporary) memory of computer system and stores
the data as long as the computer is on.
• Once the computer is turned off, the contents (data) of the RAM are
washed out. RAM is divided into two categories
17. RAM Types
Static RAM
Used as Cache
Fast Speed
Expensive
Low Storage Capacity
Dynamic RAM
Main Memory
Slower then SRAM
Cheaper then SRAM
High Storage Capacity
18. RAM Categories
DRAM
DRAM stands for Dynamic Random Access Memory. It is a combination
of cells that store data as a charge on capacitors. Each individual
memory cell in DRAM consists of a capacitor and a transistor. The
capacitor stores a small electrical charge. The presence or absence of
charge in the capacitor represents binary values (0 and 1), which are
the basic units of data storage in memory.
SRAM
SRAM stands for Static Random Access Memory. In SRAM, binary
values are stored using traditional flip-flops logic-gate configuration. It
is faster than DRAM but its storage capacity is less.
19. ROM
• ROM stands for Read Only Memory. As the name implies, the
contents of ROM can only be read. Data cannot be written into read-
only memory. ROM may contain the information on how to start the
computer and even instructions to the entire operating system
• It is a permanent memory of computer and user cannot change it
contents
20. Processing Unit(CPU Hardware Component)
The processing unit is the most important and powerful
part of computer system. It is the heart of computer
system. All calculations and other operations are
performed in this unit
21. Functions of Processing Unit
• Accepts data or instructions from input unit and stores them in
memory.
• Stores intermediate and final result of processing.
• Interprets (translate) or manipulate the instruction and send
commands to relevant units.
• Does all arithmetic operations on the data i.e. addition, subtraction,
multiplication, division etc.
• Does all logical and decision-making operations on data, i.e.
comparison of data.
• Sends the result to the output devices when required.
22. Central Processing Unit -CPU
Consist of
• CU (control Unit)
• ALU (Arithmetic & logic Unit)
• Registers
23. Control Unit
• It is the most important part of the CPU. It controls and coordinates the
activities of all other units. It performs this function by issuing necessary
commands to various components of the computer.
• The control unit fetches an instruction from the main memory by sending
an address to main memory, decode this instruction and then execute it.
Thus we can say that CU’s function is to fetch, decode and then finally
execute the instructions, which are in main memory.
OR
• The control unit interprets any instructions it receives from memory and
directs the sequence of events necessary to execute each instruction. The
control unit also establishes the timing of these events.
24. Arithmetic and logic unit
• All the arithmetical and logical activities are performed in the ALU. It
is the place where all calculations are performed and all decisions are
made. The data is temporarily transferred to ALU for processing and
results are sent back to memory.
• The ALU perform all the arithmetic operations such as Addition,
Subtraction, Multiplication or Division and Logic operations such as
the operations in which first comparison is made and then decision is
taken
25. Registers
The processor contains special storage locations called registers. These
are temporary storage devices and all the data is temporarily stored in
them before and after processing.
26. How Computer Memory Measured?
• Bit
All computers work on a binary Numbering system, i.e. they process data in one's or zero's. This 1
or 0 level of storage is called a bit.
o Byte
A byte consist of 8 bits.
o Kilobyte
A Kilobyte(KB) consists of 1024 bytes
o Megabyte
A Megabyte (MB) consists of 1024 Kilobytes
o Gigabyte
A Gigabyte (GB) consists of 1024 Megabytes
o Terabyte
A Terabyte Consist of 1024 Gigabytes
27. How Does a Computer Know what to do?
• It must be given a detailed list of instructions, called a compute
program or software, that tells it exactly what to do.
• Before processing a specific job, the computer program
corresponding to that job must be stored in memory.
• Once the program is stored in memory the compute can start the
operation by executing the program instructions one after the other.
