Chapter 4 system unit components

September 7, 2016. Wednesday

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:

•       The motherboard is the main circuit board of the system unit

•       A computer chip contains integrated circuits

Processor

•       The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer

            -Contain a control unit and an arithmetic logic unit (ALU)

      

•       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

 The step in a machine cycle

•       The pace of the system clock is called the clock speed, and is measured in gigahertz (GHz)

•       The leading manufacturers 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 up

•       Require additional cooling

             -Heat sinks

             -Liquid cooling technology

•       Parallel processing uses multiple processors simultaneously to execute a single program or task.

–      Massively parallel processing involves hundreds or thousands of processors.

Data Representation

•          Most computers are digital.

•          The binary system uses two unique digits (0 and 1)

              -Bits and bytes

A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electrical charge.

Eight bits grouped together as a unit are called a byte. A byte represents a single character in the computer.

•       ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data.

How a letter is converted to binary form and back

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:

How program Instructions Transfer in and out of RAM

•       Three basic types of RAM chips exist:

•       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.