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# Lecture 8

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Introduction to Computer All 18 Lectures of My Class

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```									INTRODUCTION TO COMPUTER                                        LECTURE 08

HOW A COMPUTER PROCESS DATA

There are two components that handle processing in a computer.
i)     Central Processing Unit (CPU)
ii)    Memory

i)   The CPU

The CPU is the brain of the computer, the place where data is
manipulated. In a microcomputer, the entire CPU is contained on a tiny
chip called a Microprocessor.
Every CPU has at least two basic parts.
a)     The Control Unit
b)     The Arithmetic and Logic Unit.

a)    The Control Unit

All the computers resources are managed from the control unit.
Control unit works as a traffic cop, directing the flow of data. The
CPU’s instructions for carrying out commands are built into the
control unit.

CPU

Arithmetic
And
Logic unit

Input                                                Output
Control Unit
Devices                                               Devices

Memory (RAM)

Storage (Hard Disk)

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PREPARED BY SADIQ A. BUGTI LECTURER BUITMS QUETTA
INTRODUCTION TO COMPUTER                                          LECTURE 08

b)    The Arithmetic And Logic Unit

As we know that the computer can perform only two types of
operations, namely arithmetic operation and logical operations.
Arithmetic includes addition, subtraction, multiplication and
division. Logical operations include comparison such as
determining whether one number is equal to, greater than, or less
than another number. Also every logical operation has an opposite
e.g. in addition operation “equal to” has “not equal to”.
Now when the control unit encounters an arithmetical or logical
instruction, it passes that instruction to the second component of
the CPU, the arithmetic and logic unit or ALU. The ALU includes a
group of registers, high-speed memory locations built directly into
the CPU, that are used to hold the data currently being processed.
For example the control unit might load two numbers from
memory into the registers in the ALU, then it might tell the ALU to
divide the two numbers or to see whether the two numbers are
equal.
ii)   Memory
Physically memory consists of chips either on the motherboard or on a
small circuit board attached to the motherboard. This electronic memory
allows the CPU to store and retrieve data very quickly.
There are two types of built in memory permanent and non permanent.
Some memory chips always retain the data they hold even when the
computer is turned off. This type of memory is called non-volatile. Other
chips in a microcomputer do lose their contents when the computer power
is shut off, these chips have volatile memory.
a)       ROM
The data in this memory cannot be changed. In fact, putting data
permanently into this kind of memory is called burning in the data,
and it is usually done at the factory at the time of manufacturing.
The data in this chip can only be read it cannot be changed so the
memory is called read only memory (ROM).
ROM contains a set of instructions, which ensure that the rest of
memory is functioning properly, check for hardware devices and
check for an operating system on the computer’s disk drives.
b)       RAM
The purpose of Random Access Memory (RAM) is to hold
programs and data while they are in use. Physically RAM consists
of some chips on a small circuit board. This memory has the
capability to access each byte of data directly. This memory will be

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PREPARED BY SADIQ A. BUGTI LECTURER BUITMS QUETTA
INTRODUCTION TO COMPUTER                                      LECTURE 08

available till our computer is on. If we shutdown our computer the
data In this memory will be lost.
RAM Technologies
years. The following are the major types of RAM used in PC
computers.
   First Page Mode (FPM) RAM
FPM RAM is the oldest and least sophisticated type of RAM, Its
still used in many PC’s available today.
   Extended Data Output (EDO) RAM
EDO RAM is faster than FPM RAM and is commonly found in the
fastest computers.

   Burst Extended Data Output (BEDO) RAM
BEDO RAM is very fast RAM and is supported by a limited
number of CPU’s manufactured by VIA.
   Synchronous Dynamic RAM (SDRAM)
SDRAM delivers burst of data at very high speeds (up to 100 MHz),
which provide more data to CPU at given time than older RAM
technologies. SDRAM is supported by popular type of RAM on the
market today.

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PREPARED BY SADIQ A. BUGTI LECTURER BUITMS QUETTA

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