The PC System unit: looking in the box

1. The PC System unit:looking in the box Unit 4 Special english For the students of computer

2. topic • 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

3. This section about • 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.

4. 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.

5. Computer on a chip: The microprocessor • 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.

6. 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 solidstate, 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.

7. Other high-speed memories • 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.

8. A fleet of buses • 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 • RoohoallahSfafdari