Topic Two: What Is A Computer

Computer can be defined as wholly electronic device or machine which is capable to accept data, and process data supplied through the available input device into information, which can be stored in the CPU memory storage unit, and also have the ability to moved processed information into the output devices such.

It can also be defined as an electronic device that is capable to accept data, and execute a series of commands (program): execute mathematical, logical operations on data given by the user and give information in the forms of an output. The output may be made obtainable either on the computer monitor or can be printed on a paper.

Thus, computer is an electronic programmable device; it receives input from the client, stores and manipulates information. It provides output in a useful drawing. It can execute both mathematical (arithmetic operation) and logical operations on the data given by the user.

Computer Features:

1. Wholly Electronic Device: - This can be described as a machine or device which performs logical and other calculating functions. 
2. Process Data: - This process data supplied by the users; and data is a set of row unprocessed facts, figures, alphabet and symbols. Computers process data to build information. 
3. Input Devices:-This input device can also be called external device, is used for performing input of texts and other function with the availability of keyboard. However, there are other devices that can also perform input of data, such as disk (CD/DVD), flash, diskette (Floppy disk) etc.  
4. Memory: - This is described as the brain box of the system where all the information are stored. 
5. Output Device: - This output devices are tools used to retrieve information saved on the memory for other purpose.

TYPES OF COMPUTE

There are different types of computer nowadays. These computers perform their variety purpose. Here we shall be looking at the classification of these computers.

1. Digital Computer 
2. Analogue Computer 
3. Hybrid Computer 
4. Mainframe Computer
5.  Super Computer 
6. Mini Computer 
7. Micro Computer 
1. Desktop Computer 
2. Laptop Computer 
3. Palmtop Computer

1.2.1 Digital Computer

The digital computer is a programmable electronic device that processes numbers and words accurately and at enormous speed. It comes in a variety of shapes and sizes, ranging from the familiar desktop microcomputer to the minicomputer, mainframe, and supercomputer. The supercomputer is the most powerful in this list and is used by organizations such as NASA (National Aeronautics and Space Administration) to process upwards of 100 million instructions per second.

Picture 1.2.1

1.2.2 Analogue Computer

A digital computer performs calculations based solely upon numbers or symbols. An analog computer, on the other hand, translates continuously changing quantities (such as temperature, pressure, weight, or speed) into corresponding voltages or gear movements. It then performs "calculations" by comparing, adding, or subtracting voltages or gear motions in various ways. The final result is sent to an output device such as a cathode-ray tube or pen plotter on a roll of paper. Common devices such as thermostats and bathroom scales are actually simple analog computers: they "compute" one thing by measuring another. They do not count.

1.2.3 Hybrid Computer

A hybrid computer is a computer system containing both analog and digital devices so that the properties or each can be used to the greatest advantage. For instance, a digital and an analog computer can be interconnected so that data can be transferred between them.

 

Types of Hybrid Computer

 Large electronic hybrid computer Systems:

Large electronic hybrid computer systems with many hundreds of operational amplifiers were widely used from the early 1960s to the mid-1980s. They solved extremely complex and extensive sets of differential equations (mathematical models) such as six-degree-of freedom space flights, exothermal chemical reaction kinetics, control systems for food processing plants, and the human immunosuppressive system.

General Purpose Hybrid Computer

General-purpose hybrid computers are hybrid computers with the ability to use different applications or to be able to solve numerous kinds of problems. Many general purpose hybrid computers were once purpose systems, either part time hybrid computers in which the outcome were achieved in a relative speed or operation computers that utilize high speed.

 

Special-Purpose Hybrid Computers

Special-purpose hybrid computers contain fixed programs permitting few or no adjustments. They are generally built into physical systems where they serve typically as a subsystem simulator, function controller or results analyzer. For example, the pneumatic computer uses air bellows and flapper nozzles to generate accurate multiplication, division, squaring, or square-root functions of input signals, and encoding data as air pressures.

1.2.4           Mainframe Computer

These computers have high storage capacity. They process large amount of data at high speed. They are used in large companies, government departments, etc., as their main computer server. These computers need low temperature and special dust free rooms. Numerous computers are connected with this computer. All the data of these computers are stored in it. These are faster and more sufficient than Minis and have a much large storage capacity. Examples are the IBM System /370 and IBM 4300 Series.

1.2.5 Super Computer

The storage capacity of super computers is much more than micro, mini and main frame computers. Super Computers are the fastest of all and can process huge amount of data within a few seconds. They are used for handling complicated applications such designing the supersonic aircraft, weather forecast, etc. India has developed a super computer called PARAM. They are most powerful and most efficient too. They are designed to process complex scientific applications. They have the computing capacity of approximately 40000000 IBM PCs. Some examples are CARY-2, ETA-10, CARY X-MP.

1.2.6 Mini Computer

These computers are more powerful than micro Computers and can support more than one user at a time. They have larger storage capacity. These computers are

used for variety of application. This machine is another advancement over the PC-AT. Here you can have a maximum of a few hundreds of dumb terminals attached to the same CPU. Processing speed is also many times faster. One example is the IBM 9375. Microprocessor used is INTEL 80286 or 80386.

1.2.7 Micro Computer

A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit (CPU). It includes a microprocessor, memory, and input/output (I/O) facilities. Microcomputers became popular in the 1970s and 80s with the advent of increasingly powerful microprocessors.

Microcomputers can be further divided into different types based on the size of their central processing unit (CPU) and other major and minor components. They are;-

1. Desktop Computer      2.Laptop Computer           3.Notebook Computer

4. Mini Tower Computer

1.2.7.1        Desktop Computer

These computers can be placed on flat smooth tables (desk) for convenience and comfort ability when in use. They are bigger than notebooks and laptops. They can also perform various complex operations. Desktop microcomputers are subdivided into their sub-devices/ parts e.g. The keyboard, monitor, system unit are all separated from one another having cables used for their connection before use unlike notebooks and laptop where all are permanently joined (connected) together when manufacture.

1.2.7.2 Laptop Computer

These are the microcomputers that can be conveniently operated on the lap. They are bigger in size and slightly heavier than the notebooks. They can perform virtually all the function of the desktop microcomputers, yet very portable like the briefcase size. They can perform complex task anywhere, anytime with ease. They are expensive compare to other microcomputers with larger sizes; this is as a result of high technology with reduction in size.

1.2.7.3 Notebook (Palmtop) Computer

These micro computers are having their sizes just like the size of exercise note books. As a result, they are handy. It runs on battery.

MINI-TOWER MICROCOMPUTERS:

These are recent modification on the system unit, whereby the system unit is made to stand erect on its own and placed beside the monitor unlike desktop which lies flat on tables and monitors placed on it. They also have their parts separately having cables for connection.

FULL TOWER MICROCOMPUTER:

These computers are closely related to the mini Tower, except that they are a bit higher and wider in physical size than the Mini Tower. All other things are the same as in Mini Tower Microcomputers.