Info about Z80 machine

On 09/22/2013 03:19 AM, Andy Collins wrote: Ah, we've been spoiled by fast hardware doing pretty much nothing. For text-mode data entry and POS and such, you don't need much CPU power (or memory, for that matter). We used a 3.5MHz 8085 and 64K to service 5 users--and that included word processing and the usual suite of business apps (AR/AP/GL). We eventually added 128K of mapped memory, but most users got by just fine with 64K. One of the aspects of implementation was that the 8085 is ill-suited to "run anywhere" code and its instruction set is pretty space-inefficient. We wrote a BASIC run-time that could time-slice between P-code like programs. Quite fast and very complex. I still have the source to the compiler and the run-time kicking around somewhere here. The compiler wasn't written in assembly, per se, but rather a macro language. The run-time pseudo-code was very compact and, in fact, outran Microsoft compiled BASIC in just about every test. There's a huge difference between general-purpose OS software such as CP/M and MP/M and a written-for-purpose OS. Incidentally, we eventually went to a 80186/80286 combination CPU running Xenix--and found to our dismay that it didn't run much faster in multi-user mode than the old 8085 system. Remember when the people in the business discussed made-for-purpose microcomputer systems. That is, you'd have an accounting "appliance" like your toaster? That seems to have vanished. We now have telephones that aim to do everything. Does generalization always win out over specialization? Should my subcompact car also serve as a 10-ton dump truck? --Chuck