Pramilah Chap 04 System Unit

Chapter 4: The Components of the System Unit
By Pramiladevi

What is the system unit?
Case that contain the motherboard, the flat board within the personal computer housing that holds the chips and circuitry that organize the computers activities.
Sometimes called chassis, is made of metal or plastic and protects the internal electronic components from damage.
The electronic components and circuitry of the system unit, such as the processor and memory, usually are part of or are connected to a circuit board called the motherboard.

What is the motherboard?
Sometimes called a system board, is the main circuit board of the system unit.
The motherboard contains several bus lines, or buses, sets of parallel electrical paths that transport electrical signals. The system bus transfers data between CPU and memory. Bus width and speed affect system performance.
Some expansion buses connect to expansion slots on the motherboard and can receive expansion boards (also called interface cards or adapter cards) that enable you to connect various peripheral devices to the computer.
A serial port enables data to be transmitted one bit at a time, while a parallel port transmit a group of bits at a time.

What is the Central Processing Unit (CPU)?
A CPU, or processor, on a chip is a microprocessor.
A microprocessor maybe called a logic chip when it is used to control specialized devices.
A microprocessor contains tiny transistors, electronic switches that may or may not allow current to pass through, representing a 1 or 0 bit, respectively.
The more functions that are combined on a microprocessor, the faster the computer runs, the cheaper it is to make, and the more reliable it is.
The 2 parts of the CPU are the control unit and the arithmetic logic unit, both working together as a team to process the computer’s command.

What is the machine cycle?
Four operation of CPU comprise a machine cycle
Step 1. FETCH
obtain program
instruction
or data item from memory
memory
Step 4. STORE
Write result to
memory
Processor
Step 2.DECODE
Translate instruction
Into commands
Control unit
ALU
Step 3.EXECUTE
Carry out command

What is memory?
Electronic components that store instruction, data, and result.
Consist of one or more chips on motherboard or other circuit board.
Each byte stored in unique location called an address, similar to seats in a concert hall.

What is Random Access Memory(RAM)?
Keeps the instruction and data for whatever programs you are using at the moment.
Divided into two types: static RAM(SRAM),which is faster, and dynamic RAM(DRAM), which is slower and much less expensive, SDRAM and RDRAM are faster and more expensive types of DRAM.

Pramilah Chap 04 System Unit

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