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Key components of the computer Classification of computers based on Purposes Classification of computers based on Signals Classification of computers based on Capacity 6/4/20162

3 1.Processor. (CPU) 2.Memory. 3.Input/Output device. (I/O) 4.Disk storage. 5.Programs.

6/4/20164 Converts raw data to information. Executes or runs programs to carry out a specific task. Sometimes called CPU when multiple chips or devices are integrated into a single unit. Is able to read from and write to the memory.

6/4/20165 Workplace of the computer. Temporarily stores programs and data. Contents can be overwritten without erasing  Random Access Memory (RAM) Volatile Stores current data and programs More RAM results in a faster system  Read Only Memory(ROM) Permanent storage of programs Holds the computer boot directions

6/4/20166 Bridge between users and computers. Input devices: keyboard, mouse etc. Output devices: printer, monitor.

6/4/20167 Holds permanent data and programs. Three major distinctions between disks and memory: a) disks have more storage. b) disks are durable. c) disks are cheaper. Common is magnetic disk (hard disk, floppy disk). Optical disk (CD-ROM,DVD-ROM).

6/4/20168 They tell computer what to do. Two kinds: system and application System programs help operate and control the computer (hardware). (the OS; Windows) Application programs carries out user tasks. (Internet Explorer).

Two types Special Purpose Computers General Purpose Computers 6/4/20169

Designed to perform a specific application. Also known as dedicated computer. Contains instructions permanently programmed into them that are designed to perform only one major function. 6/4/201610

Specialized purpose computers used to control Traffic lights Control collection of tolls in highways Used in automobiles. Weapons Appliance and Games etc 6/4/201611

Used to handle a variety of tasks. Use stored program concept – a program prepared for an application are temporarily stored in memory. Then the program can be executed to perform a specific task. After the completion of the execution of one program, another program can be used for some other task. Same hardware can be used to execute many different programs. General purpose computers are less efficient and slower than special purpose computers when applied to the same task. 6/4/201612

Two types Analog Computers Digital Computers 6/4/201613

Represents quantities by physical means like Distance Velocity Acceleration Temperature Pressure Angular position Force by mechanical or electrical parameters. 6/4/201614

Automobile speedometer – converts the rotational rate of the drive shaft of an automobile into the numerical value that represents the speed of the vehicle. Thermometer – converts the movement of a column of mercury into temperature reading. 6/4/201615

It has ability to collect and process data at high speeds. Does not require storage facility. Used to control processes of Oil refineries Steel mills Weapon systems 6/4/201616

Based on binary numbers…………that is 0 and 1 Faster Complex Efficient 6/4/201617

Capacity of data means the volume of data that a computer system can process. Measurement of capacity is based on throughput of the computer. Throughput is the amount of processing that can be performed in a given amount of time. 6/4/201618

Based on throughput they are 4 types  Micro computers  Mini computers  Mainframe computers  Supercomputers 6/4/201619

Also known as personal computers – PCs are microprocessor based small laptop or desktop or notebook systems. Personal digital assistance (PDAs) are very small portable computers. The brain of microcomputer is the microprocessor. 6/4/201620

Microprocessor – silicon chip that contains necessary circuits to perform – Arithmetic and logic operations Input/output operations A microcomputer is formed by adding Input/output capability and memory to the microprocessor. 6/4/201621

Workstation Servers Clients Terminals 6/4/201622

High speed microcomputers It has many capabilities of larger minicomputers but cost is much less. Initially it was designed to used by the engineers and designers who require powerful computing. 6/4/201623

Are not used directly. A computer network is a collection of computers connected together. They make programs and data available for users having access to a computer network. 6/4/201624

To use servers, users run desktop program called clients which knows how to contact to server and obtain information from the server. Use of desktop clients and centralized servers is called client/server computing. 6/4/201625

6/4/ Client-Sever Structure

Look like PCs but have some limitations Contains only a screen keyboard and electronics that allow them to communicate with the computer to which they are connected. Lack of process data – dumb terminals. Terminals with limited processing capabilities is called smart terminals – PCs. 6/4/201627

Performs the basic arithmetic and logic operations. Supports some of the programming languages. Physically smaller Less expensive Have small storage capability with compared to mainframe computers. 6/4/201628

As a result of low cost, ease of operations, it gains popularity in mid sixties. Some larger and expensive minicomputers are capable of supporting a number of terminals in a time-hared mode. Later years it is replaced by microcomputers. Example of manufacturer : DEC, Data General, IBM etc. 6/4/201629

A larger computer consists of modules mounted on a framework. Vary in size – between minicomputer and supercomputer. Greater processing speed. A variety of I/O devices. Greater storage capacity. Users access through a terminal 6/4/201630

Support for a number of high-speed storage devices. Multiprogramming Time sharing Operating a mainframe requires a level of efficiency – a vary large and highly trained staff. Used by large business organization Government and Military 6/4/201631

A very large and powerful mainframe computer is called a supercomputer. Applied to solve complex and sophisticated scientific problems. For national security purposes of advanced nations. Very costly – limited their development to few hundreds worldwide. Example: Cray X-MP,IBM Road Runner 6/4/201632

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6/4/ Sample questions 1. Differentiate between ‘special purpose’ and ‘general purpose’ computers. 2. Explain the basic characteristics of ‘micro computer’s. 3. What do you understand by ‘workstation’, ‘terminal’, ‘client - server’ ? 4. What are the basic criteria of ‘super computer’? 5. Define the main parts of a computer system? 6. ……