jow@unccvax.UUCP (Jim Wiley) (06/20/85)
>> One of the nicest features of the >> graphics hardware is that it uses the >> "off-phase" periods of the system >> clock, when the processor is not using >> the bus. > >This is really interesting, since the 68000 *has* no "off phase", unlike >the Motorola 8-bit chips. In fact, the 68000 is pretty much bus-bound, >and there isn't a lot of spare bandwidth to go around. There is a smell >of snake oil in the air... > >> sound and i/o for the most part run >> in the background, without taking up >> any processor time at all. > >On a machine as bus-intensive as the 68000, hardware that also wants the >bus is definitely going to slow the cpu down substantially. Maybe not as >much as if the cpu were doing the work, but it won't be trivial. Well, the 68000 does not have an "off phase" clock but a 68000 running at 8 MHz has a 500 nanosecond bus cycle. By using less that 250 nanosecond cycle time ram, the memory can be interleaved between the processor and external hardware. No bus requests, *NO* processor slow down and optimum utilization of bus bandwidth would result. It sounds like this may be what they are doing but I don't really believe that original posting. When I hear the official word, then I will believe something. Jim Wiley DATASPAN INC.