yes it does. it usually runs on a Phase Locked Loop generator for the CPU clock, (40Mhz crystal pumped into phased locked loop circuit generates an 80Mhz signal), which feeds the internal CPU clock, then gets halved, for the external I/O. (a-la Warpengine)
so a 40Mhz crystal on a phaselockedloop means a 40Mhz external, 80Mhz internal speed.
040 boards that use crystals to feed the CPU directly, no PLL circuit, (phase5/dce stuff) run the 80Mhz crystal directly to the CPU to get the 80Mhz internal speed, then gets halved for the 40Mhz external.
its why you can de-solder a 25Mhz 040 off of a blizzPPC and replace it with a 50Mhz 060, because both are fed off a 50Mhz crystal. (ignoring the obvious voltage regulator swap)
this is also why Mac quadra's were marketed as 25/50Mhz 33/66Mhz and eventually 40/80Mhz machines, about 14 years ago iirc. (were there any 20/40Mhz ones?
although in amigaland, advertising a 68040 running at 50mhz is missleading as people usually go by the external clock, so to say you're running an 040 at 50Mhz (external clock) would imply you're running a sonnet quad doubler. also popular in Mac circles. replaced a 25Mhz 040 with a special 50Mhz 040 that was doubling the already doubled 25Mhz clock for a 100Mhz internal clock, and 50Mhz external.
still with me? no? i think i lost myself too on that one :lol:
