The System Unit By: Brian Domingos Chapter 4

The System Unit System unit components are housed within the system unit or system cabinet. The three types are as follows: Desktop-contains electronic components and selected storage devices. Notebook-portable, monitor attached by hinges. PDA (personal digital assistant)-smallest, most portable, contains entire system.

Electronic Representation  Data and instructions are represented electronically with a two-state binary system of numbers (0 and 1).  Binary coding schemes convert binary data into characters. Three such schemes are: 1. ASCII-the most widely used for microcomputers. 2. EBCDIC-developed by IBM and used primarily by large computers. 3. Unicode-16-bit code to support international languages like Chinese and Japanese.

System Board The system board, also known as the mother board or the main board, connects all the system components. The system board, also known as the mother board or the main board, connects all the system components. A chip, also known as a silicon chip, is a postage stamp- sized circuitboard. A chip, also known as a silicon chip, is a postage stamp- sized circuitboard.

Microprocessor The microprocessor plugs into the system board, and is considered the brains of the system unit. The microprocessor plugs into the system board, and is considered the brains of the system unit. Two basic components of the microprocessor are the control unit and the arithmetic-logic unit. Two basic components of the microprocessor are the control unit and the arithmetic-logic unit. The control unit executes programs by directing the other system components. The control unit executes programs by directing the other system components. The arithmetic-logic unit, performs arithmetic and logical operations. The arithmetic-logic unit, performs arithmetic and logical operations.

Microprocessor Chips The two types of microprocessor chips are:  Complex instruction set computer (CISC) chips-=the basis for Intel’s Pentium III and Pentium IV microprocessors.  Reduced instruction set computer (RISC) chips-fewer instructions. They are the basis for IBM and Motorola’s PowerPC.

Memory There are three types of memory chips: There are three types of memory chips: RAM, ROM, and CMOS RAM-often called temporary or volatile because contents are lost if computer is disrupted. ROM-permanent and control essential system operations. CMOS-provide flexibility and expandability to computer systems.

Expansion Slots and Cards Example of expansion cards are:  Network adapter cards-connect to a network.  Modem cards-connect over a telephone line  Television boards-contain TV tuner and video capture capabilities, also known as personal video recorder cards.

Bus Lines Bus lines provide data pathways that connect various system components. Four principal types are: ISA (Industry Standard Architecture)-older and slower but still widely used. ISA (Industry Standard Architecture)-older and slower but still widely used. PCI (Peripheral Component Interconnect)- high speed; used to connect CPU, memory, and expansion boards. PCI (Peripheral Component Interconnect)- high speed; used to connect CPU, memory, and expansion boards. AGP (Accelerated Graphics Port)-used for video data AGP (Accelerated Graphics Port)-used for video data USB (Universal Serial Bus)-fastest; used to support high-speed devices. USB (Universal Serial Bus)-fastest; used to support high-speed devices.

Ports and Cables Ports and cables allow external devices to connect to the system unit.  Ports are connecting sockets on the outside of the system unit. The five most common types are serial, parallel, USB, and HPSB, which is also known as FireWire.  Cables are used to connect external devices to the system unit via ports.