----- Original Message ----- From: Brian White To: [email protected] Sent: Wednesday, June 27, 2018 2:59 PM Subject: Re: [M100] nn - getting back involved.
This will get a little confusing because we're talking about both main rom and option rom at the same time, so watch for that the rest of this post. The 100, 102, 200, 600, NEC all use 27C256, both for main rom and option rom *electrically*, but, in most cases the pinouts are rearranged. And it's not the same rearranging in all cases either. In most (not all) 100s main rom, and in all 100, 102, 200, nec option rom, the pinout is rearranged. Some late model 100s, all 102, 200, and 600, (not sure about nec), main rom uses normal pinout. Model 600 is the only one I know that uses normal pinout in the option rom socket. Also, the rearranged pinout for Model 100 main rom is different from the rearranged pinout for the option rom! But at least the option rom pinout is the same between all 100, 102, and 200, and I think nec too. (I don't have an nec and haven't look it up so really every time I'm trying to say "they all do X except one does Y..." I can't say if nec is included or another exception) The figtronix adapter boards are a little odd. The option rom adapters use 28C256 instead of 27C256, so that you can re-flash them without a UV eraser. One of the main rom adapters actually uses 28F256, instead of 28C256 or 27C256. I'm not sure why, but it works. 28F256 is a different pinout from 28C256 or 27C256, but electrical and signal compatible. I used it on a couple 100s. I liked it because it makes the main rom both removable and easily re-flashable because it can be removed from the pinout adapter, but it's hard to recommend, because it does require desoldering the original dip28 socket to make enough room for the new adapter and tall through-hole style plcc socket. It probably makes more sense all in all, to use the Mike Stein main rom adapter, which uses a plain dip28 27C256, with the new rom soldered to the adapter, and the combined module inserted in the original socket. Because that preserves the original mother board, and it is still physically possible to remove and update the main rom, you just need to make up a programming adapter to reverse the adapter pinout back to normal, or use a test clip to clip right on to the rom but those test clips are getting hard to find. You can't have both the original socket on the motherboard and a socket on the adapter. There isn't room in the case. Setting aside of course the other option which is that there is a way to use a REX to not only replace the main rom, but have a fully software hackable main rom after that once it's installed. But that requires installing the rex a little more permanently than usual. -- bkw On Wed, Jun 27, 2018, 11:35 AM Nickolas Nolan <[email protected]> wrote: Hi Brian, I'm not sure how much information is conflicting here. I was under the impression for 102, and I know for sure regarding NEC that the roms are 27c256 map. I have been dumping and burning my own for NEC 8201a and 8300. They don't even need carriers. SPEAKING OF.... :) i will start another thread or two for something else. The reference I have for the model 102 is here http://tandy.wiki/FigTronix again, I'm not sure how much of that documentation is correct, and I will try to look at a few more units from my trunk this weekend. I've been meaning to attempt a dump of my SuperRom in my 102. I am also hoping to find or make OSH park print for model100 static ram to compliment https://oshpark.com/shared_projects/m3Ugar47 I look forward to verifying as much as possible, and I will attempt contact the tandy.wiki owner if there are any corrections.
