Large computers are called mainframe. The term mainframe as a single word is used as a designation of large-scale computers, in contrast to a microcomputer, minicomputer, personal computer or workstation. The term mainframe comes from the use of “frame” as a device to hold electronics (rack is also frequently used), and the frame holding the electronics. The UNIVAC 1, optimized for business data processing, was an early mainframe. Mainframe computers process data at high speed, deliberate in the millions of information per second. They are very exclusive, estimate millions of dollars in some cases. Mainframe designed for multiple users and process vast amounts of data quickly. Banks, insurance companies, manufacturers, mail-order companies, and airlines are typically users. Originally, the mainframe of a computer system was the cabinet that hoisted its central processor and main memory. It is, therefore, separate from the peripheral devices (disks, printers, tape drives, etc.) and device controllers.
Mainframes are often ‘servers’ or host computers, computers that control the networks of computers for large companies, like catalog merchandiser L.L. Bean. They are multi-processor having multiple CPUs. The other computers which relieve host computer for certain routine processing requirement, are known as front-end computer, used for handling the communications to and from all the user terminals connected to the computer system. Similarly, back-end computers are used to handle data input/output operations, by data transferring to and from input/output devices of host computer. Host and other computers are located in the systems room to which entry is restricted to administrators and maintenance staffs. One The other computers which relieve host computer for certain routine processing requirement, are known as front-end computer, used for handling the communications to and from all the user terminals connected to the computer system. Similarly, back-end computers are used to handle data input/output operations, by data transferring to and from input/output devices of host computer. Host and other computers are located in the systems room to which entry is restricted to administrators and maintenance staffs or more console terminals are also located in the system room. The mainframe usually had many indicator lights (sometimes as part of operator’s console) to show fault conditions, memory contents, etc.
The central processor and main memory were housed together as an aid in increasing processing speeds (cable lengths will be short) and improving reliability (both will be at similar temperatures and humidities). For hard copy of outputs, mainframes usually have several types of printers and poltters which are connected to back-end computers. The processing speed of mainframe computers is measured in MIPS. It stands for millions of instructions per second 200-1200 MIPS. The principle architecture for that microprocessor is CISC – Complex Instructions Set Computing chip which are used in conventional mainframes and in Pcs. It can support large number large number of instructions. Typically, it was the largest component in size and cost, but modern electronics has allowed great reductions in both in recent years. In modern systems, mainframes are with very large main memory. Some memory modules are housed in cabinets separate from the mainframe. Generally, they are attached and thus become part of the mainframe cabinet. Two major vendors of mainframe systems are IBM and DEC.
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