<
jargon> Advertising raw
clock speed, instead of {bus
speed}.
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 rate 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)