CHAPTER 3 ELECTRONICS AND COMPUTER SYSTEMS
3.3. COMPUTER SYSTEM
3.1.1 Hardware
● Input – a device that enables user to enter data or command into the computer. Input device examples including keyboard, mouse, joystick, and digitizer.
● Output – a device that provide the used on information produced by computer.
The example of output devices are the monitor, printer, and plotter.
● Main memory – device that stores data, program and information produced by computer during processing. The main memory unit consisted of many cells, that each stores one information unit. There are two (2) types of main memory unit, namely, ROM (Read Only Memory) and RAM (Random Access Memory).
ROM could only be written on just once and then read many times. RAM could be repeatedly write, remove and read. Data, Program, and Information that are processed is kept in RAM, and will be lost if the computer shuts down. That is the reason why data, program, and information is kept on secondary storage media such as hard the disk, diskette, CD, etc.
● Central Processing Unit – the brain of computer that process data, program, and information. There are two (2) important parts in CPU that is Arithmetic and Logical Unit (ALU) and Control Unit. Many people refer ALU as the brain of computer. ALU responsible for two (2) basic operations, namely, arithmetics operation and matching / comparisons. While Control Unit responsible for coordination activities of other unit, such as, how to recognize keyboard and work as input device.
The physical appearance of personal computer can be seen in Figure 3.10. A PC consists of many components,
1. Display 2. Motherboard 3. CPU
4. Main Memory 5. Expansion Cards 6. Power Supply 7. Optical Disk Drive.
8. Secondary Storage (Hard Disk) 9. Keyboard
10. Mouse
Figure 3.10. Computer Hardware.
The following is a short explanation of the computer's physical components:
1. Display. Display or monitor devices is the output unit of a computer. A cable connects the monitor to a video adapter installed in the motherboard's expansion slot. Computer sent signal to video adapter to put forward characters, picture or graphics. Video adapter will convert the signal into a collection instructions for the monitor to put forward text, or picture in its screen.
Figure 3.11. Display or monitor 2. Motherboard. Motherboard also as
mainboard, system board or logic board ( Apple Computer) and sometimes shortened as mobo is the main electronics system, such as in modern computer hardware. On this board we can put other components such as, main memory, processor, video adapter, voice adapter, etc, to form a complete computer system.
Figure 3.12. Motherboard of a computer.
3. CPU. Central Processing Unit (CPU), often known as Processor, is a component in digital computer that interprets instructions and processes data as instructed by computer program. CPU provided the important part of digital system namely the ability to be programmed. CPU must be installed in every computer hardware.
Figure 3.13. Central Processing Unit (CPU).
4. Main Memory. Main Memory also known as Primary Storage, or Internal Memory, is the computer's memory with direct access to CPU without using any special input/output path.
Main memory is used to keep the actively used data. Primary storage can be formed in several type of storage, such as, main storage, cache memory, and special registers.
Figure 3.14. Several types of main memory.
5. Expansion Cards. Expansion card is a printed circuit board (PCB) that can be inserted into motherboard's expansion slot to increase computer's functionality.
The example of expansion card are video adapter, audio adapter card, network card etc.
Figure 3.15. Installation of expansion card
6. Power Supply. Power supply also known as Power Supply Unit (PSU) is the equipment to supply the required energy mainly electrical power in a computer.
Figure 3.16. Power Supply Unit.
7. Optical Disc Drive. Optical Disc is a secondary storage media with a disc like shape. Data kept in an optical disc may be accessed through the help of a laser beam onto the disc. There are two (2) major types of optical disc, namely, CD (Compact Disc) and DVD (Digital Versatile Disc). The device to read, write, or erase in an optical disc is known as Optical Disc Drive.
Figure 3.17. CD-RW Drive, an example of Optical Disc Drive.
8. Secondary Storage (Hard Disk). Secondary Storage is a device used to help the Primary Storage (main memory), especially to keep data, program, or information that will be used again. Different from primary storage, data, program and information in secondary storage will not be lost even the computer is shutdown, except if it is deliberately removed.
Secondary storage often used in a computer is Hard Disk. Hard disk keeps the data in a magnetic disc in certain patterns to represent the data.
Figure 3.18. Hard Disk 9. Keyboard. Keyboard is a device to
type in text or character into a computer. This device also provides special control keys in computer.
Figure 3.19 shows the layout of a keyboard.
Figure 3.19. General layout of a keyboard 10. Mouse. Mouse is usually a pointing device that can be used to detect relative
movement in two dimensional plane to be display later on the screen. Mouse sometimes equip with other functions, such as, wheel. In addition, mouse play role in command execution through a its left / right button of either single click or double click.
Figure 3.20. Various types of mouse.