Computers can be classified as general purpose or special purpose. General-purpose computers are used to perform a variety of applications and the most common in business while special purpose computers are used for specific or limited applications e.g. military or scientific research. Computers can be classified by size or by use
Categories of Computer Systems (by size)
They are also called Personal Computers (PCs) or Desktop Computers. These are relatively small and inexpensive.
They consist of a single processor or a chip
The system is normally made up of the microprocessor, keyboard, VDU one or two floppy disk drives, a printer and a hard disk drive. It has a hard disk capacity of 20Mb to 520Mb
May use a colour or monochrome cathode ray tube (CRT)
Have capabilities for networking.
They are single user.
They occupy little space.
They are capable of multiprogramming.
They are compatible with a wide range of software.
PCs come in a variety of sizes: notebooks (handheld), laptops, desktops and floor standing. Minicomputer System (Mid-range Computers)
They are systems the size of a small table that can accommodate a number of users at a time. They have storage capability larger than personal computers. They can support a variety of transaction processing activities
-Support magnetic tape storage
-They are multi-user more than 100 users at time for super minis -Have multiple hard disks, both fixed and exchangeable
-Can be upgraded when necessary
-They do not require a special environment to work so can allow for decentralisation. -They are less expensive than the mainframe systems
-They have bigger capacities than microprocessors, some have 32 bit microprocessors. Mainframe computers