I somewhat, vaguely recall this posting last summer from you. I had my mind on other things as there were painters in the house and they were doing more damage than good. That being said I would like to make this one statement very clear concerning this project.
SIGN ME UP!! Late last year I bought a T102 from a eBay seller. The seller was very iffy about the 102 status. It was under $100 so I thought why not. Was very disappointed to find out it would not power on or do anything batteries or not. Subsequent investigation led me to find that the power hardware on the main board suffered some type of damage, corrosion, burn out. Well I'm not the creative hardware type, at the moment I thought why not build a Z 80 version of the main board? I figured after 35 or so years a lot of the support chips and circuitry required for a Z 80 in any M100 series must be smaller on demands for circuitry now. Taking a second look, cassette interface, audio, etc (cause why not?), I feel the effort to be now, daunting. I'm still looking to fix my T102, but the idea of an add on faster processor is fine as well. Please keep us posted. I reiterate, SIGN ME UP!! > On Jul 11, 2019, at 10:30 AM, Stephen Adolph <twospru...@gmail.com> wrote: > > Motivated by 2 things > 1) discovery of the NSC800 Z80 processor that is 80C85 like > 2) continuing to work in the direcition of CP/M > 3) and recalling that there are 5MHz 80C85 parts out there.. > > I started to work on a dual CPU card for M100 that enables a couple of things; > - standard 2.5MHz 80C85 operation (default) > - switchable clock for 80C85, supporting 5MHz > - switchable CPU enabling NSC800 at 2.5 MHz. > > Board is done and heading to the fab. VHDL is mostly done. > > I don't expect this board will be wildly popular but maybe it has some > interest Double speed M100 seems interesting on it's own, let alone being > able to support Z80 CP/M applications. > > > Any interest? > > I have purchased material to make 5 of these. > > A few more comments. > - to install this board you need to remove the 80C85. that's some effort to > do > - to run at 5MHz you need to upgrade the 81C55 to a 5MHz version. That's > also some effort. > - NSC800 runs about 5$ 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. > > >
