Different Computer Types

There are different computer types available depending on the number of users they can support simultaneously.

1. Supercomputers – These types of computers are very expensive, very fast, and the most powerful computers in the world. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation (CDC). Supercomputers using custom CPUs traditionally gained their speed over conventional computers through the use of innovative designs that allow them to perform many tasks in parallel, as well as complex detail engineering.

The chief difference between a supercomputer and a mainframe is that a supercomputer channels all its power into executing a few programs as fast as possible, whereas a mainframe uses its power to execute many programs concurrently. They are quite rare they are mainly used in scientific research stations such as in nuclear stations and weather forecasting stations, animated graphics, fluid dynamic calculations, nuclear energy research, weapons simulations, submarine tracking, pattern matching (in the biosciences), fluid dynamics and materials simulations, graph analyses, cryptology and petroleum exploration.

Supercomputer systems have the capability to enable scientists to solve scientific problem that are more complex and pursue new studies in atmospheric chemistry, systems biology catalysis and materials science.

2. Mainframe computers — These are large and expensive computer types capable of supporting hundreds, or even thousands, of users simultaneously. In the hierarchy, mainframes are just below supercomputers. Nearly all mainframes have the ability to run (or host) multiple operating systems, and thereby operate not as a single computer but as a number of virtual machines. In this role, a single mainframe can replace dozens or even hundreds of smaller servers. In some ways, mainframes are more powerful than supercomputers because they support more simultaneous programs. But supercomputers can execute a single program faster than a mainframe.

3. Minicomputers — Minicomputers are midsized computers. In size and power, minicomputers lie between workstations and mainframes. In the past decade, the distinction between large minicomputers and small mainframes has blurred, however, as has the distinction between small minicomputers and workstations. But in general, a minicomputer is a multiprocessing system capable of supporting from 4 to about 200 users simultaneously.

NB; Users connects to the mainframe or mini computers using dumb terminal – using a keyboard and monitor: - A display monitor that has no processing capabilities. A dumb terminal is simply an output device that accepts data from the CPU. In contrast, a smart terminal is a monitor that has its own processor for special features, such as bold and blinking characters. Dumb terminals are not as fast as smart terminals, and they do not support as many display features, but they are adequate for most applications.

4. Microcomputers (Personal computers) – The term microcomputer is generally synonymous with personal computer (PC), or a computer that depends on a microprocessor. Microcomputers are designed to be used by individuals, whether in the form of PCs, workstations or notebook computers. A microcomputer contains a central processing unit (CPU) on a microchip (the microprocessor), a memory system (typically read-only memory and random access memory), a bus system and I/O ports, typically housed in a motherboard.

Microcomputers can be further classified as either; desktop or portable computers.

Desktop PCs

Desktop computers are not built to be mobile. They are moved, but only to a new desktop location and with the power supply inactive. There are a number of major differences between computers that are intended to be used in one place as a desktop and portables or mobiles that can be easily moved from one location to another.

Desktop computers are large and heavy in comparison to portables. They can be carried in specially manufactured cases, but only to assist a support engineer in moving, not as a frequent procedure. The monitor, keyboard and mouse are all separate items on a desktop.

Desktop computer components and devices, although quite resilient to movement while active are not made to be constantly moved, even less so when they are operational. A mains power supply is mandatory, as desktop computers cannot work without a constant supply of electrical power.

The desktops can further be subdivided depending with the casing type, Tower casing and desktop casing.

For tower casing, the motherboard is placed on side of the system unit, while the other major components like the power supply, and mass storage devices are stacked on top of each other in a cabinet. One main advantage with computers using the tower casings is that there is ample space for future upgrades for example if you wish to add more storage devices.

For the desktop casings, the motherboard lies on the bottom and is parallel to the desk or table. The system unit is usually smaller and more compact. It is not a very good choice if you are going to install other drives like another hard disk or a DVD writer. One main advantage is that they are small and thus will occupy less space. The placement is also ideal since it will lie on top of a desk and then you can place your TFT monitor on top.

NB: You can flip over the tower casing and end up with a desktop and you can turn your desktop to a tower literally though but the problem will be your drives will be facing sideways. So you will always have a problem inserting or removing your CDs because they will keep on falling, other drives might fail to access your CD or DVD contents due to the awkward position.

The size of the casing determines how much space you need on your desk to place the PC. If you have a small desk with limited space, you might consider the smaller mini computer case. If space is not an issue, then you can go for the tower casing where there are more functions. If you are adding a lot of computer parts to your system, you might consider getting a tower case. A small, crammed up case will increase the heat generation and result in the overloading of the power supply.

Portable or mobile computers are manufactured specifically to be portable (are designed for mobility). They:

• are small, compact and light in weight;
• can be accommodated in a carry case, produced with compartments for the computer and for various portable computer attachments.

Portables are produced in a variety of sizes:

Generally the smaller computers have less functionality and may require specific operating system software to operate. There is also very small hand-size systems called Personal Digital Assistants (PDAs) that use a special stylus for input and can be linked to desktop or other portable systems for uploading and downloading data.

 PDAs Palmtop, Handheld or Pocket PCs Smart Phones, are some of the names that these small computers are known as, but basically they provide the same types of functions and feature.

Typically PDAs offer standard applications such as a diary, calculator, To Do list, address book and a contact list.