• PRESENTED BY

•MUHAMMAD JUNAID ABBASI

SYSTEM CLOCK• It is an ELECTRONIC component &

generates ELECTRIC signals at a fast speed.

• It controls all functions of computer using clock ticks, These ticks are known as CLOCK CYCLE.

• The speed at which CPU executes instructions is called CLOCK SPEED.

• Processor speed is measured in MHz and GHz.

SYSTEM CLOCK

MIPS• MIPS stands for Millions Of

Instructions Per Second.• Speed of workstations and some

server computer is measured in MIPS.• Computer can operate up to several

thousand MIPS.• Workstations can perform 100 or

more and mainframes can perform 200-1,200 MIPS.

FLOPS• FLOP stands for Floating Point

Operations Per Second.

MEMORY• Data and Instructions are stored in

memory to be executed. They are stored in memory as bytes

during execution.• Each byte in the memory has its unique

address that identify its location.• It is also called Primary storage.

MEMORYMemory Stores the following three

items:1. Operating system and other

system software.2. Application programs3. Data

MEMORYThere are two types of Memory.• VOLATILE Memory: Loses its contents when computer is

turned off.• NON VOLATILE Memory: Doesn't loses its contents when

computer is turned off.

Random Access Memory

• Random access means that each individual byte in the entire memory is directly accessible.

• RAM is used to store an ever changing parade of programs and data.

• A program must be loaded into the RAM before execution.

• It is also called VOLATILE memory.

TYPES OF RAMMemory comes in variety of forms.

There are two main types of RAM.• Static RAM• Dynamic RAM

Static RAM• The memory cells are made of digital

gates.• Each cell can store its value without any

need to refresh the data as long as the power is available.

• CPU doesn't wait to access data.• It’s normally used to build a very fast

memory known as CACHE memory.

Dynamic RAM• It is the type of memory that is used in

most computers.• DRAM requires an electric current to

maintain its electrical state.• The electric charge of DRAM decrease

with time that may result in loss of data.• The processor cannot access the data of

DRAM when it is being refreshed.

Difference b/w SRAM n DRAM

SRAM DRAM

• It is faster then DRAM.

•It is slower than SRAM.

• It is more expensive.

•It is less expensive.

•It does not need to be power-refreshed.

•It has to be refreshed after each read operation.

•It utilizes less power. •It utilizes more power.

Memory Module• RAM is mounted on a small circuit

board called MEMORY MODULE.• This memory is mounted on the

mother board.

There are three types of memory module.

• SIMM• DIMM• RIMM

Types of memory module

• SIMM Stands for Single Inline Memory Module.

• In this Module pins on the opposite sides of the circuit board are connected together to form a single set of contacts.

SIMM

DIMM• DIMM stands for Double Inline

Memory Module.• In this module the pins on opposite

sides of the circuit do not connect and form two set of contacts.

RIMM• RIMM stands for Rambus Inline

Memory Module.• It houses SDRAM chips.

Read Only Memory• Rom stores data instructions

permanently.• These stored instructions cannot be

changed or deleted.• When the power is switched off the

instructions stored in it are not lost, that’s why it is also called NON-VOLATILE memory.

• It contains small set of instructions called ROM BIOS.

Types of ROMDifferent types of ROM are as

follows:• PROM• EPROM• EEPROM

PROM

• PROM stands for programmable Read Only Memory.

• This form of ROM is initially blank, user can write data on it using special devices.

• If there is any error in writing the instructions, the error can not be removed from the PROM.

EPROM• It stands for Erasable

Programmable Read Only Memory.• User can erase data stored in

EPROM chips by exposing the chip to ultra violet light.

EEPROM• It stands for Electrically Erasable

Programmable Read only Memory.• In this memory user can read &

write instructions using ELECTRICAL PULSES.

• If there is any error, the user can erase the contents ELECTRICALLY.

Difference b/w RAM n ROM

RAM ROM•It is temporary memory

•It is Permanent memory.

•It enables data to be both read & written to memory.

•It enables data to only read to memory.

•Data can be changed or deleted.

•Data can not be changed or deleted.

Difference b/w RAM n ROM

RAM ROM

•Instructions are written at the time of execution.

•Instructions are written at manufacturing time.

•Instructions in Ram are continuously changing.

•It is not possible to write new instructions on RAM.

•It’s volatile memory.

•It’s non-volatile memory.

Difference b/w PROM n EPROM PROM EPROM

•Instructions written on it can not be erased.

•Instructions written on it can be erased.

•If there is an error while writing on PROM, it becomes unusable.

•If there is an error while writing on EPROM, it can still be used again.

•The user can write instructions on PROM only once.

•The user can write instructions on EPROM many times.

REFRENCES• The concepts of Information Technology BY………..IT SERIES• Information Technology “THE BREAKING WAVE” BY………… IRWIN MCGRAW-HILL• WWW.GOOGLE.COM• WWW.ENCYCLOPEDIA.COM

THANK `s

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