Mainframe

= __//**Mainframe**//__ =

__//**Definition of Mainframe:**//__ A very large and expensive computer capable of supporting hundreds, or even thousands, of users simultaneously. 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.

// Differences from supercomputers //
A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers are used for scientific and engineering problems which are limited by processing speed and memory size, while mainframes are used for problems which are limited by data movement in input/output devices, reliability, and for handling multiple business transactions concurrently. The differences are as follows:
 * Mainframes are measured in millions of instructions per second while assuming typical instructions are integer operations, but supercomputers are measured in floating point operations per second. Examples of integer operations include moving data around in memory or checking values. Floating point operations are mostly addition, subtraction, and multiplication with enough digits of precision to model continuous phenomena such as weather prediction and nuclear simulations. In terms of computational ability, supercomputers are more powerful.
 * Mainframes are built to be reliable for transaction processing as it is commonly understood in the business world: a commercial exchange of goods, services, or money. A typical transaction would include the updating to a database system for such things as inventory control (goods), airline reservations (services), or banking (money). A transaction could refer to a set of operations including disk read/writes, operating system calls, or some form of data transfer from one subsystem to another. This operation does not count toward the processing power of a computer. Transaction processing is not exclusive to mainframes but also used in the performance of microprocessor-based servers and online networks.

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