Amazing work, Steve, it’s inspiring. Thanks for the update. CAM
-- C.A. Magaret Sent from my newfangled mobile technogizmo. Please forgive any typos, inelegant brevity, or nonsensical auto-corrections. > On Oct 4, 2020, at 06:23, Stephen Adolph <[email protected]> wrote: > > > The NSC800 does need slightly different main ROM code compared to 80C85. The > interrupt functions are different. I've patched the main ROM, and you can > see the "Mike Stein" adapter there, allowing a 27C256. Again plug and play. > > <20201004_075734.jpg> > > > So with this set up, I have (as far as I can tell) a fully working Model 100. > The only hardware difference is that the Cassette port does not work at all. > There is no SID or SOD signal on the NSC800. > > Of course the major difference is that the NSC800 supports all of the Z80 > opcodes but none of the 80C85 undocumented opcodes....which are quite popular > in a lot of M100 software! > > So, I'm finding that a lot of native M100 3rd party software like ROMs, and > utilities like TS-DOS and TEENY don't run on NSC800. Ah, so be it. > > So to be honest if you want an M100 to run M100 applications then... this is > not for you. > But, if you want to run CP/M, well, this has potential! > > To complete this as a CP/M rig, I have done a 2 more things. > 1) I've added a REXCPM. I use it only for CP/M, no REX functionality > 2) I have implemented a new BCR hack for video. More on this later. > 3) I use MVT100 to drive an external LCD. > > <20201004_081229.jpg> > > So here you see a few things ;). > The M100 is attached to MVT100 via a 9 pin serial cable plugged into the BCR > port. > The MVT100 is sending a VGA signal to the monitor. > I've installed a "slightly modified" version of Philip Avery's M100 CP/M > > And, on the LCD you can see the startup screen for Turbo Pascal. PROVING it > is a Z80! > > A bit more about some of this. > Why did I change the BCR hack? Well, the original hack used the SOD signal > on the 80C85, which does not exist on the NSC800. So, I redesigned the hack > to use the REMOTE control for the Cassette. Now it works for both processor > types. This hack consists of a single wire + a capacitor, and does not > impact use of the cassette for 80C85. > What changes did I make to CP/M? > Philip has already provided a variant of M100 CP/M that removes all 8085 > undocumented opcodes, so what I changed was the "CASS" external video code, > to use the new BCR hack. > > For CP/M, you always have to define your terminal. In the case of MVT100, > you need to configure applications to use the control codes of MVT100, which > are... VT100. > > Anyhow that's a catch up for you all on this project. > All I can say is, it seems like there are thousands of ways things can find a > way to not work. But it is satisfying when you get enough of the problems > out of the way. > > With all of these changes, I can revert this laptop to a standard M100 by > swapping the processor and the ROM. The BCR hack can remain and has no > impact on standard operation. > > Steve
