Chapter 4

• Differentiate among various styles of system units on desktop computers, notebook computers, and mobile devices
• Identify chips, adapter cards, and other components of a motherboard
• Describe the control unit and arithmetic logic unit components of a processor, and explain the four steps in a machine cycle
• Identify characteristics of various personal computer processors on the market today, and describe the ways processors are cooled
• Define a bit and describe how a series of bits represents data
• Explain how program instructions transfer in and out of memory
• Differentiate among the various types of memory
• Describe the purpose and types of expansion slots and adapter cards, and differentiate among slots for various removable flash memory devices
• Differentiate between a port and a connector, and explain the differences among a USB port, FireWire port, Bluetooth port, SCSI port, eSATA port, IrDA port, serial port, and MIDI port
• Describe the types of buses in a computer
• Explain the purpose of a power supply and describe how it keeps cool
• Understand how to clean a system unit on a computer or mobile device

What is a 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 Drive Bay(s), Power Supply, Sound Card, Video Card, Processor, Memory.
• The main circuit board of the system unit is Motherboard
• A computer chip contains integrated circuits

What is 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

What is 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. Example [The operating system and other system software, Application programs, Data being processed and the resulting information]
• 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 which are Volatile memory and Nonvolatile memory

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

There are some type of basic types of RAM chips exist

Dynamic RAM (DRAM)

Static RAM (SRAM)

Magnetoresistive RAM (MRAM)