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 Computer Components (Complete Chapter Notes)

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Posts : 47
Join date : 2012-10-31

PostSubject: Computer Components (Complete Chapter Notes)   Wed Sep 11, 2013 12:36 pm

2.1 Computer Program
The set of instructions (commands) given to the computer to process data is called a computer program.

2.2. Electronic data processing (EDP)
The process of performing arithmetic and logical operations with the help of computer is known as Electronic Data Processing.
2.3 System unit
The system unit is the main body of the computer. It contains a number of other components which are enclosed in a rectangular casing.
2.4 System Software
A set of computer programs that are designed to control and manage the actual operations of the computer hardware is known as system software.
2.5 CPU
Central Processing Unit (CPU) is the main and most important unit of computer. It is generally referred to as the brain of the computer. It accepts data and instructions from the input unit and stores into its memory.
2.6 CU
Control Unit (CU) consist of electronic circuitry that generates signals to direct the entire computer system to carry out or execute the programs. The control unit coordinates the components of a computer system.
2.7 Port
The input, output and communication devices are connected to the computer through a socket known as port. It enables an external device to connect to the computer.
2.8 Elements of EDP
There are five basic elements in a processing system which uses a computer for processing data. These are hardware, software, user program, procedure and personnel’s.
All the physical parts which makes up a computer system called hardware i.e. all the devices or peripherals which performs the data processing operations.
Software consists of programs and routines whose purpose is to make the computer useable for the user. These software normally supplied by computer manufacturers or software manufacturers.
A program consist of a related instructions to perform operations. A data processing job may require a number of programs.
The operations of data processing system requires procedure for use, in preparing data, for operating the computer and distributing the output after processing.
E.D.P basically needs three kinds of skilled personnel’s.
a) System Analyst
b) Programmer
c) Operator
System Analyst studies information needs and data processing requirements, design a data processing system and prepare specification.
A Programmer writes a programmer on specification by System Analyst.
An Operator is a person who operates the computer system.
Application Software
A set of programs used to solve the problems of users is called application software. Application software is also known as software package. The examples of software packages are word processors, spreadsheets, database etc.

2.9 Computer Bus
In computer the term bus refers that paths between the components, actually bus, is a group of a wire. The bus is the common path way through which the processors send/receive data and commands to/from primary and secondary storage and all can transport 8 bits at a time whereas a bus with 16 lines can transport 16 bits at a time.
2.10 Types of Computer Bus
There are two main buses in a computer:
1. Data Bus
2. Address Bus
2.10.1 Data Bus
The data bus is an electrical path that connects the central processing unit (CPU) memory, and the other hardware devices on the motherboard. The number of lanes on a highway effects how long it takes people to get to their destinations. Because each wire can transfer one bit at a time, an eight-wire bus can move eight bits at a time. A 16-bit bus can transfer two bytes and a 32-bit bus can transfer four bytes at a time. Actually, the bus is a group of parallel wires. The number of wires in the bus affects, the speed at which data can travel between components, just as
2.10.2 Address Bus
The second bus that is found in every micro computer is the address bus. The address bus is a set of wires similar to the data bus, but is connects only the CPU and memory and all it carries are memory addresses. The reason that the address bus is important is that the number of lines in it determines the maximum number of memory address. For example, one byte of data is enough to represent 2 = 256 different values, if the address bus could carry only eight bits at a time, the CPU could address only 256 bytes of memory. Most of the early PCs had 20-bit address bus, so the CPU could address only 2(20) bytes or 1 MB of data.
2.11 Computer Ports
A system board with its processor and memory unit can work only when linked to input/output storage and communication devices to receive data and communicate results of processing. Peripheral devices such as a keyboard, mouse, monitor and a printer come with a cable and a multiple connector. To link a device to the PC, you plug its connector into a receptacle called a port in much the same way you plug a lamp cord into electrical outlet. A port is one of the entry lines coming into the computer. A port provides a direct link to the microcomputer's common electrical bus.
2.12 Types of Computer Ports
There are two types of ports used in computer:
1. Serial Ports
2. Parallel Ports
2.12.1 Serial Ports
A serial port provides a connection for transmitting data one bit at a time. A serial port connects your computer to a device such as modem, which requires two-way data transmission, or to a device such as a mouse, which requires only one-way data transmission. IBM-compatible computers use either 9-pin or 25-pin connectors for their serial ports COM1, COM2 etc.
2.12.2 Parallel Ports
A parallel port provides a connection for transmitting data eight bits at a time over a cable with eight separate dta lines. Parallel transmission is fast because eight bits travel simultaneously. Parallel transmission is typically used to send data to the printer. The cable that connects two parallel ports contains 25 wires, eight wires carry data and the remaining wires carry control signals that help to maintain orderly transmission and reception. IBM-compatible computes generally allow you to use up to three ports which are designated as LPT1, LPT2 etc.
2.13 Memory Unit
Memory unit is the place where the computer program and data are stored during processing. It is the area, through which all the data which is input into or output of the CPU must pass. It is monitored by OU which keeps track of every thing in the storage. It is a random access device, which consists of thousands upon thousands of storage locations, each of which can be directly reached by the CU. Each storage location is distinguished by the address.
2.14 Types of Memory Unit
It is divided into two parts:
1. Read Only Memory (ROM)
2. Random Access Memory (RAM)
2.14.1 Read Only Memory (ROM)
This part of memory contains permanently stored information. When the power is switched off. ROM does not wash away. This information is available to a computer to read and process but not to be changed is kept on ROM. This information is stored on small pieces of memory chips, before the computer is assembled.
2.14.2 Random Access Memory (RAM)
This part of memory consists of blank chips and hence the computer can use it to store and retrieve (write and read) information during its processing. The information stored in RAM is volatile, that is, when the computer is shut down the stored information is lost.
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