cyclebabble

jargon Advertising raw clock speed, instead of busspeed.

IBM uses raw clock speed as the speed of the computer. In

the IBM PC and IBM PC XT, the clock is divided by 4 to

produce the 4-phase bus clocks. Thus a 4 MHz IBM XT really

runs at 0.895 MHz, because that 4 MHz was really 3.58 MHz

which gets divided by four.

A Tandy Color Computer ran at exactly the same speed, but

clock speed was specified as bus speed, 0.895 MHz, leaving the

impression that it was 4 times slower. Actually it ran a

little faster with a more efficient instruction set. If the

actual clock frequency had been specified on a CoCo 3, it

would have been 14.32 MHz, although the bus speed was still

0.895 MHz. That high speed also generated video, color, and

hidden refresh timing.

100 MHz computers are running at bus speeds of around 25 MHz.

(1997-02-13)