Chapter Four - The Components of the System Unit

 A. The System Unit

The system unit is the main part of a computer that contains electronic components used to process data. The case of the system unit protects the electronic components in the system units from damage. The case can be made from metal or plastic. All computers and mobile devices have a system unit that located in different place depending on each device.

             Sometimes, we might have to open the unit system to replace or reinstall the components. Some of the system unit’s components, which include the processor, memory, adapter cards, drive bays, and the power supply.

1.     Motherboard

            Sometimes also called as system board, is the main circuit board of the system unit. There are many electronic components attach to the motherboard, there are also some built into it.

 B.      Processor

Also called as CPU (Central Processing Unit) is the component that processes instructions to operate a computer. 

On a personal computer, all of the processor’s functions are on a single chip. Some microprocessor are multi-core processor, dual-core processor, and quad-core processor.

    1.  The Control Unit

Is a component of a computer and processor and  that directs and coordinates the operations of the computer and processor.

 

    2. The Arithmetic Logic (ALU)

Is used to perform arithmetic, comparison, and the other operations as a part of processor.

    3.     Machine Cycle

A processor repeats a set of four basic operation for every instruction, they are:

        ·       Fetching

        ·       Decoding

        ·       Executing

        ·       Storing

 

4.     The System Clock

Is a small quartz crystal circuit to control the timing of computer operations. Clock Speed is measured by the number to ticks persecond.

5.     Comparison of Personal Computer Processors

The most widely used processor chips are Intel and AMD. Now, processor chip manufacturers used a numbering scheme that reflects the processing speed.

 

C.    Data Representation

            Most computers are digital, so they only recognize on and off, that also can be represent by two digits, 0 and 1. The 0 means off, and 1 means on.

            Computers use binary system. The binary system only has two digits called bits, they are 0 and 1. By itself, a bit is not very informative but when 8 bits are grouped together, they form a byte. Coding Scheme is the combinations of 0s and 1s that represent characters are defined by patterns.

D. Memory

To store instructions, data needed by those instructions, and the results of processing the data (information).

Memory stores three categories of items:

·       the operating system and other system software

·       application programs

·       the data and the result (information)

1.     Bytes and Addressable Memory

To access data or instructions, the computer references the addresses that contain bytes of data.

2.   Memory Sizes

           

3.     Types of Memory

     There are two types of memory: Volatile and Nonvolatile. Volatile Memory loses contents when the computer’s turned off. Meanwhile the Nonvolatile Memory doesn’t loses its contents.

4.     RAM

     Also called as main memory. RAM consists of memory chips that can be read and written to by the processor and other devices.

5.     Cache

Memory cache stores frequently used instructions and data.

6.     ROM

ROM is nonvolatile. The data cannot be modified because the data is readonly.

7.     Flash Memory

Is a non-volatile memory chip that can be erased and rewritten. It’s also used for storage and for transfering data.

8.     CMOS

CMOS (complementary metal-oxide semiconductor) provides high speeds and consumes little power.

9.     Memory Access Times

 

 

E. Expansion Slots and Adapter Cards

Expansion slot refers to any of the slots on a motherboard that can hold an adapter card.

Adapter card (expansion card), is any internal expansion card that allows the computer to communicate with another peripheral and enhances functions of a component of the system unit.

Peripheral is ancillary device used to put and get information and that connects to the system unit and is controlled by the processor in the computer.

1.     Removable Flash Memory

Removable Flash Memory includes these three devices:

·       Memory cards

·       USB flash drives

·       PC Cards/Express Card modules

F.    Ports and Connectors

Ports is a connecting place between the computer and other computers or peripheral devices so that the peripheral can send data to or receive information from the computer.

Connectors connect a cable to a port. A cable connector at one end attaches to a port, and a connector at the other end attaches to a port on the peripheral.

1.     USB Ports

 

 

 

 

 

2.     FireWire Ports

Similar to a USB port. It can connect multiple types of devices. FireWire allows us to connect up to 63 devices together.

3.     Other Ports

·       Bluetooth Port

·       SCSI Port

·       eSATA Port

·       IrDA Port

·       MIDI Port

4.     Port Replicators and Docking Stations

Ports replicators is an external device that attaches to peripherals.

Docking stations is an external device that attaches to mobile computer or device

 

G.  Buses

            Is a communication system that allows the various devices attached to the system unit to communicate with each other.

H.  Bays

Is an opened computer system section which you can install additional equipment.

I.    Power Supply

Is a hardware component of system unit that supplies power to an electrical device by converting the AC power into DC power. Some external peripherals have an AC Adapter.

To keep the power supply cool, there is a fan built in the power supply.