1. System Unit By Sam Gibbs

2. System Unit The main part of a personal computer Includes a chassis, microprocessor, main memory, bus, and ports Does not include the keyboard, monitor, or any peripheral devices

3. Chassis Every computer system contains at least on chassis to house the circuit boards and wiring A metal frame that serves as the structural support for electronic components There are two basic flavors of chassis designs-desktop models and tower models

4. Chassis II If you want to insert more boards than there are slots, you will need expansion chassis, which provide additional slots

5. Desktop and Towers Tower model refers to a computer in which the power supply, motherboard, and mass storage devices are stacked on top of each other in a cabinet Desktop is stored in a more compact box It is more of an advantage to have a tower model because of fewer space constraints, which makes additions easier to install

6. Microprocessor A silicon chip that contains a CPU (Central Processing Unit) Microprocessor and CPU are compatible Microprocessors can control the logic in nearly all digital devices, from clock radios to fuel injection systems for automobiles

7. Three basic characteristics differentiate Microprocessors Instruction set: The set of instructions that the microprocessor can execute Bandwidth: The number of bits processed in a single instruction Clock speed: Given in Megahertz (MHz), the clock speed determines how many instructions per second the processor can execute

8. Main Memory Refers to the internal memory in the computer The word “Main” is used to distinguish it from external mass storage devices, such as disk drives Another term for main memory is RAM (Random Access Memory)

9. Main Memory cont. The computer can manipulate data that is only in the main memory Every program you execute and every file you access must be copied from a storage devices into the main memory The amount of memory is crucial because it determines how many programs can be executed at one time and how much data can be readily available to a program

10. Bus A collection of wires through which data is transmitted from one part of the computer to another Can be referred to as an “Internal Bus” -this connects all the internal computer components to the CPU and the main memory Also, “Expansion Bus” -enables expansion boards to access the CPU and memory

11. All Buses consist of 2 parts An Address Bus A Data Bus The Data Bus transfers actual data whereas the Address Bus transfers information about where the data should go

12. Port An interface on a computer which enables you to connect a device Internally, there are numerous ports connecting disk drives, display screens, and keyboards Externally, personal computers have ports for connecting modems, printers, mice, cameras, and other peripheral devices