Steve, Not owning a 100 I can't dive into this but I am definitely watching to see what you come up with. The 5mhz upgrade is really interesting. I do wonder what that will do to all the apps that have specific timing (ie: TS-DOS delay). Will the clock get messed up?
But if this leads to CP/M then the existing ROM and applications don't really matter. Kurt On Thu, Jul 11, 2019, at 7:31 AM, Stephen Adolph wrote: > Motivated by 2 things > 1) discovery of the NSC800 Z80 processor that is 80C85 like > 2) continuing to work in the direcition of CP/M > 3) and recalling that there are 5MHz 80C85 parts out there.. > > I started to work on a dual CPU card for M100 that enables a couple of things; > - standard 2.5MHz 80C85 operation (default) > - switchable clock for 80C85, supporting 5MHz > - switchable CPU enabling NSC800 at 2.5 MHz. > > Board is done and heading to the fab. VHDL is mostly done. > > I don't expect this board will be wildly popular but maybe it has some > interest Double speed M100 seems interesting on it's own, let alone being > able to support Z80 CP/M applications. > > > Any interest? > > I have purchased material to make 5 of these. > > A few more comments. > - to install this board you need to remove the 80C85. that's some effort to do > - to run at 5MHz you need to upgrade the 81C55 to a 5MHz version. That's also > some effort. > - NSC800 runs about 5$ on ebay. > - fast 80C85 can be had for under 5$. > - fast 81C55 can be had for under 5$. > - to run at 5MHz you might also find you need a faster main ROM, and faster > RAM. TBD on that; will advise after I do some testing. > > >
