clock rate

clock rate

<processor, benchmark> The fundamental rate in cycles per second at which a computer performs its most basic operations such as adding two numbers or transfering a value from one register to another. The clock rate of a computer is normally determined by the frequency of a crystal. The original IBM PC, circa 1981, had a clock rate of 4.77 MHz (almost five million cycles/second). As of 1995, Intel's Pentium chip runs at 100 MHz (100 million cycles/second). The clock rate of a computer is only useful for providing comparisons between computer chips in the same processor family. An IBM PC with an Intel 486 CPU running at 50 MHz will be about twice as fast as one with the same CPU, memory and display running at 25 MHz. However, there are many other factors to consider when comparing different computers. Clock rate should not be used when comparing different computers or different processor families. Rather, some benchmark should be used. Clock rate can be very misleading, since the amount of work different computer chips can do in one cycle varies. For example, RISC CPUs tend to have simpler instructions than CISC CPUs (but higher clock rates) and pipelined processors execute more than one instruction per cycle. (1995-01-12)

In computing, the clock rate or clock speed typically refers to the frequency at which the clock generator of a processor can generate pulses, which are used to synchronize the operations of its components, and is used as an indicator of the processor's speed. It is measured in clock cycles per second or its equivalent, the SI unit hertz (Hz).

main memory

<storage> (Or "core") An early form of non-volatile storage built (by hand) from tiny rings of magnetisable material threaded onto very fine wire to form large (e.g. 13"x13" or more) rectangluar arrays. Each core stored one bit of data. These were sandwiched between printed circuit boards(?). Sets of wires ran horizontally and vertically and where a vertical and horizontal wire crossed, a core had both wires threaded through it. A single core could be selected and magnetised by passing sufficient current through its horizontal and vertical wires. A core would retain its magnetisation until it was re-magnetised. The two possible polarities of magnetisation were used to represent the binary values zero and one. A third "sense" wire, passed through the core and, if the magnetisation of the core was changed, a small pulse would be induced in the sense wire which could be detected and used to deduce the core's original state. Some core memory was immersed in a bath of heated oil to improve its performance. Core memory was rendered obsolete by semiconductor memory. For example, the 1970s-era NCR 499 had two boards, each with 16 kilobytes of core memory. (1996-03-04)

Financial Core (also known as FiCore or Fi-Core) refers to a legal carve out that permits workers opposed to participating in a labor union to be employed under the benefits of a union's contracts without compelling them to be a member of that union.

Magnetic-core memory was the predominant form of random-access computer memory for 20 years between about 1955 and 1975.

Common Object Services Specification in CORBA.