Generation of computers

Computer

An automatic electronic machine used for making calculations for controlling operations that are expressible in numerical or logical terms.

Ancestor of computer

§  Mechanical

§  Electromechanical

Mechanical computer

An example of mechanical computer is PASCALINE. This is also known as arithmetic machine.  It was described in 1624.

Charles Babbage discovered two types of mechanical computer. The first one is difference engine and the second one is analytical engine. The first programmer in analytical engine was Lady Ada Lovelace.

The first electromechanical computer is the Mark-1.

Generation of computer

Computers can be classified based on the technology used, switching device used, storage device used, switching time used and software developed etc. This can be considered as generation of computers.

First Generation

In first generation of computers vacuum tubes are used as active devices. Vacuum tubes generate great heat. So the operating lifetime of the devices is reduced. Also due to the heat, air conditioner is needed for the operation of the devices. In 1964 first electronic computer emerged by professors of Pennsylvania is called ENIAC (Electronic Numerical Integrator And Computer). It has low memory and takes 200µs for addition and 2800 µs for multiplication. ENIAC contained 17,468 vacuum tubes, 7,200 crystal diodes, 1,500 relays, 70,000 resistors, 10,000 capacitors and around 5 million hand-soldered joints. It weighed more than 30 tons, took up 1800 square feet and consumed 150 kW of power. It has an execution time of 5000 additions/sec. The next computer was EDVAC (Electronic Discrete Variable Automatic Computer). In 1950s production of stored program computers begins. One of the early computers was UNIVAC (UNIVersal Automatic Computer) which uses 1000 vacuum tubes. It was the first commercial computer. The next was BINAC (BINary Automatic Computer).

Second generation   

In this generation transistors are used as active devices. Transistors are less expensive, require little power and generate less heat. Computers become small in size and faster in operation. In 1955 invention of magnetic cores for storage was one of the achievements in this generation. This type of magnetic cores is used to make large random access memory (RAM). Memory capacities of second generation computers are that of 100kb. Magnetic disc storage was also developed in this period. Operating system also developed. Commercial application increased in this period. Professionals in computing such as system analyst, programmer etc where emerge. Ex: IBM 700

Third generation

Third generation computers were introduced in 1964. In this generation the active device transistor is replaced by ICs (Integrated Circuit). It has facilities for time sharing and multi programming. These computers are much faster and smaller than second generation computers. Size of main memory reached up to 4MB. High level languages like FORTRAN-4, COBOL-68 were emerged in this period. Ex: IBM 370

Fourth generation   

Micro computers are used in this system. This uses large scale integrated circuit (LSI) and very large scale integrated circuit (VLSI) technologies. Magnetic core memory is replaced by semiconductor memory in this period. An important development in this period is interfaces to graphic systems. CAD (Computer Aided Design) started in this period.    

Fifth generation computers

In the fifth generation, the VLSI technology became ULSI (Ultra Large Scale Integration) technology, resulting in the production of microprocessor chips having ten million electronic components. This generation is based on parallel processing hardware and AI (Artificial Intelligence) software. AI is an emerging branch in computer science, which interprets means and method of making computers think like human beings. All the high-level languages like C and C++, Java, .Net etc., are used in this generation.

The main features of fifth generation are:

·         ULSI technology

·         Development of true artificial intelligence

·         Development of Natural language processing

·         Advancement in Parallel Processing

·         Advancement in Superconductor technology

·         More user friendly interfaces with multimedia features

·         Availability of very powerful and compact computers at cheaper rates

Classification of computers based on size and shape

1.      Microcomputers

Micro computers are small, low cost and single user digital computer. They consist of CPU, input unit, output unit, storage unit and the software. IBM PC based on Pentium microprocessor and Apple Macintosh are some examples of microcomputers.

2.      Minicomputers

Mini computers are digital computers, generally used in multi user systems. They have high processing speed and high storage capacity than the microcomputers. Minicomputers can support 4-200 users simultaneously. The users can access the minicomputer through their PC’s or terminal. They are used for real time applications in industries, research centers etc. Ex: IBM 8000 series.

3.      Mainframe computers

Mainframe computers are multi user, multi programming and high performance computers. They operate at a very high speed, have very large storage capacity and can the workload of many users. Mainframe computers are large and powerful systems generally used in centralized databases. The user accesses the mainframe computer via a terminal that may be a dumb terminal, an intelligent terminal or a PC. A dumb terminal cannot store data or do processing of its own. It has the input and output device only. An intelligent terminal has the input and output device, can do processing, but cannot store data of its own. The dumb and the intelligent terminal use the processing power and the storage facility of the mainframe computer. Mainframe computers are used in organizations like banks or companies. Ex: IBM ES000

4.      Supercomputers

Supercomputers are the fastest and most expensive machines. They have high processing speed compared to other computers. The speed of supercomputer is generally measured in FLOPS (Floating Point Operations Per Second). Supercomputers are built by interconnecting thousands of processors that can work in parallel. Supercomputers are used in weather forecasting, nuclear research etc. Ex: PARAM  

Hardware and Software

The digital computer operates in the binary system. The data inside a computer is in binary form of 0’s and 1’s. The instruction is also represented in the form of 0’s or 1’s; such a program is said to be in machine language. All computers work in machine language. Machine language is a difficult language for human beings to understand. To remove this difficulty, there are special programs called compilers which accept programs in high level languages and translate them into machine language programs.

The physical units in a computer, such as the CPU, Memory, Input and Output units, form the hardware. Software represents the set of programs that govern the operation of a computer system and make the hardware run. Software can be classified into two, system software (ex: operating system) and application software (MS Office). The hardware works as dictated by the software. The operating system is special software that manages the hardware and software.

Firmware

Firmware is a combination of hardware and software. ROMs, PROMs and EPROMs that have data or programs recorded on them are firmware. Ex: BIOS

PC Components

Here are the components needed to assemble a basic modern PC system:

·         Motherboard

·         Processor

·         Memory(RAM)

·         Case (chassis)

·         Power Supply

·         Floppy Drive

·         Hard Disk

·         CD – ROM Drive

·         Keyboard

·         Mouse

·         Video Card

·         Monitor (Display)

·         Sound Card

·         Speakers

·         Motherboard

The motherboard is the core of the system. Motherboards are available in several different shapes or form factors. The motherboard usually contains the following individual components:

Ø  Processor socket (or slot)

Ø  Processor voltage regulators

Ø  Motherboard chipset

Ø  Level 2 cache

Ø  Memory SIMM or DIMM sockets

Ø  Bus slots

Ø  ROM BIOS

Ø  Clock/CMOS battery

Ø  Super I/O chip

The chipset controls the CPU or processor bus, the L2 cache and main memory, the PCI bus, the ISA bus, system resources etc.

The ROM BIOS contains the initial POST program, bootstrap loader, drivers for items built into the board, and usually a system setup program (often called CMOS setup or BIOS setup) for configuring the system.

·         Processor

The processor is also called CPU. It is the single most important chip in the system, as it is the primary circuit that carries out the program instructions of whatever software is being run.

·         Memory (RAM)

The system memory is often called RAM for Random Access Memory. This is the primary memory that holds all the programs and data the processor is using at a given time. Memory is normally installed in a modern system in SIMM or DIMM form.

·         Case (Chassis)

The case is the frame or chassis that houses the motherboard, power supply, disk drives, adapter cards, and any other physical components in the system. There are different styles of cases available from desktop to tower models.

·         Power Supply

The power supply is what feeds electrical power to every single part in the PC. The main function of the supply is to convert the 230V AC into the 3.3V, 5V and 12V power that the system requires for operation.

·         Floppy Disk Drive

The floppy drive is a low capacity, removable media, magnetic-storage device.

·         Hard Disk Drive

The hard disk is the high capacity storage media for the system. It is used to contain copies of all programs and data not currently active in main memory.

·         CD – ROM Drive

CD and DVD ROM drives are relatively high capacity, removable-media, optical drives; most newer systems include drives featuring write/rewrite capability.

·         Keyboard

The keyboard is an input device on a PC that is used by a human to communicate with and control a system.

·         Mouse

Mouse is also an input device that enables a user to point or select items show on the screen.

·         Video card

The video card controls the information you see on the monitor.

·         Monitor (Display)

Monitors are generally classified by three criteria – diagonal size in inches, resolution in pixels and refresh rate in Hertz (Hz).