Computer Knowledge - Exam Oriented
Main Frame Computers, Mini Computers and Micro-Computers
Main frame computers are large scale general purpose computer systems. The word Main frame has its origin in early computers which were big in size and required large frame works to house. Main frame computers have large storage capacities in several million words. Secondary storage directly accessible by these computers is of the order of several billion words. These computer systems have one or more CPUs and can support a large number of terminals (upto 100 or more). These computers are fast in operation (approximately 100 million instructions/sec) and accept all types of high level languages. Word length in these computers is 16 or 32 or 64 bits.
Mini computers are general purpose computer systems with reduced storage capacity and performance as compared to main frame computers. These computers operate at a CPU speed of few million instructions/sec, These computers can also accept all types of high level languages and word length in these computers is 16 or 32 bits. These can support upto about 20 terminals. With the fast development in electronics, it has become difficult to draw a line of demarcation between small main frame computers and large Mini Computers.
Micro computers are small sized computers which utilize micro-processors The CPU of a micro computer is usually contained on one chip. Microcomputers have low storage capacity maximum being of the order of 256 K words and are slow in operation (approximately 100 thousand instructions/sec). Microcomputers are usually provided with video display Unit, floppy drive and printer. Some microcomputers can support hard disks also. Commonly Used language on these microcomputers is BASIC. However they can also accept other high level languages viz. PASCAL, FORTRAN etc. Maximum word length of these computers is 16 bits. However most of these use 8-bits words.