----- Original Message ----- From: Kurt McCullum To: Model 100 Discussion Sent: Monday, May 04, 2015 3:51 PM Subject: Re: [M100] new EU M100 main ROM / REX compatibility.
> Mike, > Would the same diodes + resistor modification work for all model T machines? > Or just the 100? I've seen your adapter board and noticed that it says it's > only for the 100. > Kurt ----- >> On Monday, May 4, 2015 12:36 PM, MikeS <[email protected]> wrote: >> ...And of course if you're handy you can add a socket with a couple of >> diodes and a resistor and use a '512 instead of the '256 to add an Option >> ROM while you're at it (e.g. TS-DOS). >> m ------------ I don't have a 200 so I can't say; perhaps Steve can. In the 102 of course you have the issue that the system ROM is soldered in and would have to be removed or at least disabled, and you might not have enough room unless you were prepared to cut a trace or two on the system board and put the EPROM right into the holes where the ROM was. I have been meaning to experiment with some of the smaller and lower-profile OTP EPROMs and EEPROMs one of these days; the original prototype even had provisions for extra RAM for a poor man's REX, but considering Steve's reasonable prices it didn't seem worth while. As to the various other M100/102 more-or-less-compatibles I expect that there wouldn't be any problem as long as the ROM is removable with a standard JEDEC 27256 pinout. Here's a picture of the 'Poor (cheap? ;-) man's' version, just using an ordinary IC socket instead of the adapter board; you could probably even get away with just piggybacking the EPROM:
