The Components of the System Unit
by พีรนนท์ วัฒนพงษ์
1. Processor
1.1. The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer
1.1.1. Contain a control unit and an arithmetic logic unit (ALU)
1.2. The control unitis the component of the processor that directs and coordinates most of the operations in the computer
1.3. The arithmetic logic unit(ALU) performs arithmetic, comparison, and other operations
1.4. For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle
1.5. Most current personal computers support pipelining
1.5.1. Processor begins fetching a second instruction before it completes the machine cycle for the first instruction
1.6. The pace of the system clock is called the clock speed, and is measured in gigahertz(GHz)
1.7. The leading manufacturers of personal computer processor chips are Intel and AMD
1.8. Determine how you plan to use a new computer before selecting a processor
1.9. A processor chip generates heat that could cause the chip to burn up
1.10. Require additional cooling
1.10.1. –Heat sinks –Liquid cooling technology
1.11. Parallel processing uses multiple processors simultaneously to execute a single program or task
1.11.1. Massively parallel processing involves hundreds or thousands of processors
2. Data Representation
2.1. Analogsignals are continuous and vary in strength and quality
2.2. Digital signals are in one of two states: on or off
3. Memory
3.1. Memoryconsists 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
3.2. Memory size is measured in kilobytes(KBor K), megabytes(MB), gigabytes(GB), orterabytes(TB)
3.3. The system unit contains two types of memory:
3.3.1. Volatile memory
3.3.1.1. Loses its contents when power is turned off
3.3.1.2. Example includes RAM
3.3.2. Nonvolatile memory
3.3.2.1. Does not lose contents when power is removed
3.3.2.2. Examples include ROM, flash memory, and CMOS
3.4. Flash memorycan be erased electronically and rewritten
3.4.1. CMOStechnology provides high speeds and consumes little power
3.5. Access timeis the amount of time it takes the processor to read from memory
3.5.1. Measured in nanoseconds
4. Expansion Slots and Adapter Cards
4.1. An expansion slotis a socket on the motherboard that can hold an adapter card
4.2. An adapter cardenhances functions of a component of the system unit and/or provides connections to peripherals
4.2.1. Sound card andvideo card
4.3. With Plug and Play, the computer automatically can configure adapter cards and other peripherals as you install them
4.4. Removable flash memory includes:
4.4.1. Memory cards, USB flash drives, and PC Cards/ExpressCardmodules
5. Buses
5.1. A busallows the various devices both inside and attached to the system unit to communicate with each other
5.1.1. –Data bus –Address bus
5.2. Word sizeis the number of bits the processor can interpret and execute at a given time
5.3. Expansion slots connect to expansion buses
6. Keeping Your Computer or Mobile Device Clean
6.1. Clean your computer or mobile device once or twice a year
6.2. Turn off and unplug your computer or mobile device before cleaning it
6.3. Use compressed air to blow away dust
6.4. Use an antistatic wipe to clean the exterior of the case and a cleaning solution and soft cloth to clean the screen
7. Objectives Overview
7.1. Differentiate among various styles of system units on desktop computers, notebook computers, and mobile devices
7.2. Identify chips, adapter cards, and other components of a motherboard
7.3. Describe the control unit and arithmetic logic unit components of a processor, and explain the four steps in a machine cycle
7.4. Identify characteristics of various personal computer processors on the market today, and describe the ways processors are cooled
7.5. Define a bit and describe how a series of bits represents data
7.6. Explain how program instructions transfer in and out of memory
7.7. Differentiate among the various types of memory
7.8. Describe the purpose and types of expansion slots and adapter cards, and differentiate among slots for various removable flash memory devices
7.9. Differentiate between a port and a connector, and explain the differences among a USB port, FireWire port, Bluetooth port, SCSI port, eSATAport, IrDA port, serial port, and MIDI port
7.10. Describe the types of buses in a computer
7.11. Explain the purpose of a power supply and describe how it keeps cool
7.12. Understand how to clean a system unit on a computer or mobile device
8. The System Unit
8.1. The system unitis a case that contains electronic components of the computer used to process data
8.2. The inside of the system unit on a desktop personal computer includes:
8.2.1. Drive bay(s)
8.2.2. Power supply
8.2.3. Sound card
8.2.4. Video card
8.2.5. Processor
8.2.6. Memory
8.3. The motherboardis the main circuit board of the system unit
8.3.1. A computer chipcontains integrated circuits
9. Ports and Connectors
9.1. A portis the point at which a peripheral attaches to or communicates with a system unit (sometimes referred to as a jack)
9.2. A connectorjoins a cable to a port
9.3. On a notebook computer, the ports are on the back, front, and/or sides
9.4. A USB portcan connect up to 127 different peripherals together with a single connector
9.4.1. You can attach multiple peripherals using a single USB port with a USB hub
9.5. A port replicator is an external device that provides connections to peripherals through ports built into the device
9.6. A docking station is an external device that attaches to a mobile computer or device
10. Bays
10.1. A bayis an opening inside the system unit in which you can install additional equipment
10.1.1. A drive baytypically holds disk drives