Unit 4

Special english For the students of

computer

THE PC SYSTEM UNIT:

LOOKING IN THE BOX

the motherboard :

Micro processor (main processor)

Support electronic circutity

Memory chips

Expansion board.

Computer on the chip : micro processor

The processor : cpu and units.

Ram

Other high-speed memories

A Fleet of Buses

TOPIC

The processor ,RAM,and a variety of other electronic components are housed in the system unit, usually a metal and plastic upright box(the

rower) or inside the laptabs shell. In this section ,well look inside the box at at the major electronic components of a computer system.

THIS SECTION ABOUT

THE MOTHERBOARD :

A single circuit board , provides the path through which the processor communicates with memory components and peripheral devises. The processor as the PCs brain and the motherboard as the PCs central nervous system.In a PC, the following are attached to the motherboard :

Micro processor (main processor)Support electronic circuitry (for example on chip handles input/output signals from the peripheral devises) Memory chips (for example , RAM and other types of memory)Expansion board. (optional circuit board such as a Fax/modem)

The various chips attached to the motherboard and, therefore , to a common electronic bus that enables data flow between the various system components.

The microprocessor smaller than a postage stamp and fond in wristwatch and CD player. We used the term chip to refer to any self-contained integrated circuit.in a few year ,virtually everything mechanical or electronic will incorporate microprocessor technology into it is design.

The processor : runs the show and is the nucleus of any computer system .sometimes called the central processor unit or CPU , it has only tow fundamental section : control unit and arithmetic and logic unit .these unit work together with random access memory(RAM) and other internal memory.

THE control unit :The processor is the nucleus of the computer system ,the control unit is the nucleus of the processor. It has three primary function:

To read and interpret program instructions .

To direct the operation of internal processor components.

To control the flow of program and data in and out of RAM.

The processor contains high-speed store area called register that can store no more than a few bytes .because register reside on the processor chip.

COMPUTER ON A CHIP: THE MICROPROCESSOR

The Arithmetic and logic unit: it performs all computations (addition , subtraction, multiplication and division) and all logic operation.

A logic operation compares tow pieces of data , ether alphabetic and numeric.

Ram a read –and- write memory , enables data to both read and written to memory. RAM is solid state, that is, it is electronic circuitry with no moving part.

In contrast to permanent storage on disk, RAM provides the processor only with temporary storage for programs and data.

The data in RAM are manipulated by the processor according to program instruction. A program instruction or a piece of datum is stored in a specific RAM location called an address.

COMPUTER ON A CHIP: THE MICROPROCESSOR

Data and program are being continually moved in and out of Ram at electronic speeds. But that’s no enough. To faster transfer of instructions and data to the processor , computer are designed with cache memory. Cache memory is increase computer system throughput.

Another special type of internal memory, called read-only memory (ROM) can not be altered by the user.

A variation of ROM is programmable read-only memory such as flash-memory.

OTHER HIGH-SPEED MEMORIES

The motherboard includes several empty expansion slots that provide direct connections to the common electrical bus. Thes slots let you expand by expandion board , also

called expansion cards.

Expenions boards are made to fit a particular type of bus

Roohoallah Sfafdari

A FLEET OF BUSES