Computer application: Computer Application #4 System Unit Components

The System Unit

The system unit is a case that contains electronic components of the computer used to process data.
The inside of the system unit on a desktop personal computer includes :

Processor

The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer.
The control unit is the component of the processor that directs and coordinates most of the operations in the computer.
The arithmetic logic unit (ALU) performs arithmetic, comparison, and other operations.
For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle.
Most current personal computers support pipelining - processor begins fetching a second instruction before it completes the machine cycle for the machine cycle for the first instruction.
The processor contains registers, that temporarily hold data and instructions.
The system clock controls the timing of all computer operations.
The space of the system clock is called the clock speed, and is measures in gigahertz (GHz)
The leading manufactures of personal computer processor chips are Intel and AMD.
Determine how you plan to use a new computer before selecting a processor.
A processor chip generates heat that could cause the chip to burn u.
Require additional cooling

Parallel processing uses multiple processors simultaneously to execute a single program or task - Massively parallel processing involves hundreds or thousands of processors.

Data Representation

Analog signals are continuous and vary in strength and quality.
Digital signals are in one of two states : on or off.
Most computers are digital.
The binary system uses two unique digits ( 0 and 1 )
Bits and bytes.
ASCII ( American Standard Code for Information Interchange ) is the most widely used coding scheme to represent data.

Memory

Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data.
Stores three basic categories of items :

Each location in memory has an address.
Memory size is measured in kilobytes (KB or K), megabytes (MB), gigabytes (GB), or terabytes (TB).
The system unit contains two types of memory :

Volatile memory : Loses its contents when power is turned off . / Example includes RAM
Nonvolatile memory : Does not lose contents when power is removed. / Examples include ROM, flash memory, and CMOS.

RAM chips usually reside on a memory module and are inserted into memory slots.
The amount of RAM necessary in a computer often depends on the types of software you plan to use.
Memory cache speeds the processes of the computer because it stores frequently used instructions and data.
Read-only memory (ROM) refers to memory chips storing permanent data and instructions.
A PROM (programmable read-only memory) chip is a black ROM chip that can be written to permanently.
Flash memory can be erased electronically and rewritten - CMOS technology provides high speeds and consumes little power.
Access time is the amount f time it takes the processor to read from memory - Measured in nanoseconds.

Expansion Slots and Adapter Cards

An expansion slot is a socket on to motherboard that can hold an adapter card.
An adapter card enhances functions of a component of the system unit and/ or provides connections to peripherals. - Sound card and video card
With Plug and Play, the computer automatically can configure adapter cards and peripherals as you install them.
Removal flash memory includes : - Memory cards, USB flash drives, and PC Cards/Express Cared modules

Ports and Connectors

A port is the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack).
A connector joins a cable to a port.
On a notebook computer, the ports are on the back, front, and/or sides.
A USB port can connect up to 127 different peripherals together with a single connector - You can attach multiple peripherals using a single USB port with a USB hub.
Other types of port include :

A Bluetooth wireless port adapter converts a USB port into a Bluetooth port.
A smart phone might communicate with a notebook computer using an IrDA port.
A port replicator is an external device that provides connections to peripherals through ports built into the device.
A docking station is an external device that attaches to a mobile computer or device.

Buses

A bus allows the various devices both inside and attached to the system unit to communicate with each other :

World size is the number of bits the processor can interpret and execute at a given time.
Expansion slots connect to expansion buses.
Common type of expansion buses include :

Bays

A bay is an opening inside the system unit in which you can install additional equipment. - A drive bay typically holds disk drives

Power Supply

The power supply converts the wall outlet AC power into DC power.
Some external peripherals have an AC adapter, which is an external power supply.

Keeping Your Computer or Mobile Device Clean

Clean our computer or mobile device once or twice a year.
Turn off and unplug your computer or mobile device before cleaning it.
Use compressed air to blow away dust.
Use an anti static wipe to clean the exterior of the case and a cleaning solution and soft cloth to clean the screen.

Computer application