daveh@cbmvax.cbm.UUCP (Dave Haynie) (10/08/86)
> The 6809 was really too late to play a serious role in the 8-bit market > which was by then dominated largely by the Z-80, though it was quite > nice for what it was, and even at its relatively slow 2 MHz processor > clock speed, showed better throughput figures than the 4 MHz Z80s > available at the time. This is a bit off the subject, but none-the-less relevent. Maybe I'm just more sensitive to it having been designing 6502 family computers for a few years, maybe not. But I see time and time again, all over the Usenet world and beyond, from folks who obviously otherwise know what they're talking about. Yes, once again, we have dreaded words like clock speed, MHZ, cycle time used in a meaningless fashion. In the above example, the 6809, doing one memory cycle per clock tick at 2MHz, considered "relatively slow" as compared to a 4MHz Z-80, even though the Z-80 takes 3 ticks for op-code fetches (equivalent to a 6809 with a 1.333 MHz clock), and 4 ticks for all other operations (equivalent to a 6809 with a 1MHz clock). Fortunately for the 68000 versus 808x wars, both base-level processors run 4 tick memory cycles (except for 5 tick 808x I/O cycles), so the clock speed isn't a real issue. Of course, its coming up again with the newer 68020/68030 machines on this side, and the 80386 over there. I don't know if folks out there are really confused about this or not, but it really looks that way. If only those people who really understand the relations between clock and bus speed use in in their examples, maybe the others who aren't quite straight on it will catch on, and then we'll all know what everyone else is talking about. Let's wipe out MHZ abuse in our lifetime! -- ============================================================================ Dave Haynie {caip,ihnp4,allegra,seismo}!cbmvax!daveh "Techno-Hippie, heathen, designing evil computers" These opinions are my own, though if you try them out, and decide that you really like them, a small donation would be appreciated.