Ch - 2 COMPUTER COMPONENTS

Computer is the combination of Hardware and Software, Hardware is the physically parts of the computer and software are the programs of the computer.

Computer Hardware
The physical components of a computer system, including any peripheral equipment such as printers, modems, Keyboard, mouse, RAM, ROM, harddisk, motherboard etc are called computer hardware.

Computer Software
The software that runs on computer for a specific purpose is called computer software. Like Operating system i.e. DOS, Windows, Unix, Application Programs i.e. Ms-Office, Games, Languages, movies etc.

MAIN COMPONENTS OF COMPUTER

A digital computer system has the following three basic components.
1. Input Devices. 2. Central Processing Unit (CPU). 3. Output Devices.

1. Input Devices.
The peripheral devices, which is used to provide or send data to processor is called input devices, such as keyboards, mice, joysticks, Mouse, Scanner, Digital camera etc.

2. Central Processing Unit (CPU)
The CPU is the device that interprets and executes instructions. Single-chip central processing units, called microprocessors. The CPU-or microprocessor, in the case of a microcomputer-has the ability to fetch, decode, and execute instructions and to transfer information to and from other resources over the computer's main data-transfer path, the bus. By definition, the CPU is the chip that functions as the "brain" of a computer. CPU consists two parts ALU and CU.

i. Arithmetic Logical Unit. (ALU)
The ALU is a collection of register, arithmetic and logic circuits. A register is a location in ALU stored data on temporary basis. ALU perform all arithmetic and logical activities, i.e. Addition, subtraction, multiplication and division, and also used for logical comparisons, such as equal to (=), greater than (>), less than (<), not equal (<>), greater than or equal (>=) and less than or equal (<=).

ii. Control Unit (CU)
In simple words to perform right function at right time and in proper way inside the computer is the duty of Control unit. The main duties of the CU to save data, print data, receive data from input devices; retrieve data from hard disk to RAM etc.

3. Output devices
The computer work divided into three categories first we input data with the help of input devices. The CPU processes it. And at last with the help of output devices we can see our data output/result in form of information. The main output devices are Monitor, Printer & Speakers etc.

BUSES.
A bus is a group of electrical conductors (usually wires) running parallel to one another that can carry a charge from point a to point b. These conductors can be copper traces on a circuit board or wires in a cable. Usually, they are found in multiples of eight (8, 16, 32, 64, and so on). Early computers used eight conductors for the main system bus, thereby allowing the transmission of eight bits, or one byte, of information at a time.

Data Bus
The Bus that sends data between processor and other devices is called data bus. 8 bits data bus transfer one word (1 byte) at a time, as 32 bits data bus transfer (4 bytes) at a time. The number of wires depends on the speed of data bus.

Address Bus
The address bus is a set of wires similar to the data bus. It is connects only the CPU and memory, which carries information about location of data. It is used to identify the address of the location, where date to be transfer or send. This bus speed is also depend on the bus size.

Control Bus
The set of lines within a computer that carry control signals between the CPU (central processing unit) and other devices. For example, a control bus is used to indicate whether the CPU is attempting to read from memory or to write to it. The duty of this bus is supervision that checked the flow of the data.

COMPUTER MEMORY
The device or location where information can be stored and retrieved is called computer memory. There are two types of memory, which is used in a computer.

1. Main memory / Primary memory
The main storage region to which the microprocessor has directs access data. It is also called computer internal memory. It is directly attached with CPU and other devices. The operation performance is very fast here. RAM and ROM are the examples of this memory.

RAM (Random Access Memory)
RAM is Semiconductor-based memory that can be read and write by the central processing unit chip, which is fixed on the motherboard. All the computer processing performs here. It is also called temporary memory. RAM retrieves data from secondary storage devices and also sends back after processing. A computer speed depends on size of RAM.

ROM (Read only Memory)
It is also a chip, which is fixed on motherboard. The information stored in ROM permanently. Generally the ROM has information about computer configuration, boot to operating system, check all input/output devices at booting timing. It is also called non-volatile (permanent) memory.

2. Secondary memory / Auxiliary memory / Backup storage devices
This memory is also called external memory. Secondary memory is not directly attached with CPU. The role of this memory is very important in computer. We stored our information i.e. Operating system, Application programs like MS-Office, Languages, Games etc. It is permanently memory of computer. Examples of this are Hard disk, Floppy disk, Compact disk, Magnetic tap etc.

COMPUTER PORTS
Normally ports are located on the back of the CPU, where we attached the input and output devices with computer. As we connected keyboard in keyboard port, mouse in mouse port, monitor in monitor port, printer in printer port and as Modem, NIC card, Scanner etc, shortly every device have his own port. The ports that have pins are called male ports and the ports, which have holes, are called female ports. There are two types of ports one is Serial and other is Parallel port.

Serial Ports
Serial ports are used for serial data communication, such as mice, modem, mouse, digital camera etc. The process of this type of ports is slow, because the transmission of data in form of one bit. These ports are internally named as COM1, COM2 etc.

Example: A= 0100 0001 Serial Ports 0100 0001

Parallel Ports
In this type of ports the transmission is in parallel form. Data transfer from one location to another location in form of 8, 16 or 32 bits at a time. As the speed of transmission is fast to compared with Serial Ports. Normally printer used parallel port. These ports are internally named as LPT1, LPT2 and LPT3 etc.