Unknows S-100 System

Using the 8085 instead of a Z-80 was absolutely the right decision (and if you are wondering, who made that decision ..... it was me). The objective was to do a dual processor system with an 8088 and some 8-bit CPU that would run CP/M. It would have been extremely difficult to have done that with a Z-80, it was trivial with an 8085 (using a Z-80 would probably have taken an additional almost 2 dozen ICs ... the external hardware and bus interfaces and signals were just totally different). Further, the performance of the 8085 was (ok, arguably) higher .... true, we were stuck with the 8080 instruction set, but the 8085 ran at 5MHz (later 6MHz) with FAR better timing margins than a 4MHz Z-80. There were things that, in retrospect, we might have done differently (strapping the 8088 for "min" mode instead of "max" mode, for example), but using the 8085 wasn't one of them. All commercial software used 8080 instructions, and the machine was primarily for running MS-DOS anyway. From our perspective (as the manufacturer) we never felt a downside to that decision. Barry Watzman Former computer product line director Heathkit and Zenith Data Systems On Friday 21 September 2007 13:56, Chuck Guzis wrote: I wonder why they went with that part? I seem to remember some others that used it as well, though specifics are not coming to mind at the moment. I have a bunch of those on hand, and think about doing something with them chip and a single address latch, I just haven't decided yet what I'm gonna do with it.