Great news! Question for you: I know the dual-CPU board doesn't physically fit into the socket space in the NEC machines, but would your single NSC800 adapter fit just fine?
Gary On Thu, Jul 23, 2020 at 7:38 PM Stephen Adolph <twospru...@gmail.com> wrote: > > Update. > I have refined my NSC800 aka Z80 conversion for M100 somewhat. > > I now have a very simple adapter board that converts the 80c85 socket to > accept NSC800. Small and simple. Plug and play. > > The main rom needs to change to a patched version that I have. To do so, you > need to use one of the various means to convert the strange M100 main rom > socket to something more standard. > > Why? > > Well I am still pushing towards a nice Z80 solution for CP/M. > > Besides.. the solution is so clean it is really cool. Hard to resist! The > M100 could have easily been designed with this processor to begin with. > > So why not ;) > > My thinking is to offer this as a simple kit or maybe even just release the > board. The BOM is really small. Processor is easy to get off ebay. > > One thing that would be nice, is a new version of tsdos that avoids all the > special 80c85 opcodes....compatible with 8080. Then it could run on z80 as > well. > > Even a patched teeny would be fine I suppose. > > > > > On Thursday, July 11, 2019, Stephen Adolph <twospru...@gmail.com> 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. >> >> >>
