The problem is that the new adapter is too tall for the available space, if it's plugged in to the original socket.
The reason it's too tall is because of the plcc socket. Through-hole style plcc sockets are pretty tall. The way that adapter works, you lose the ability to plug the original rom back in, but but the new rom is removable and rewriteable without any further special adapters. You just pop the bare chip out and it pops into a standard reader, with an adapter too, but a standard one that comes with the reader just to adapte the physical form, notrearrange pins into a special pinout. There are lots of possible work-arounds, but they all have some kind of down-side just like desoldering the original socket is a down-side. You could make a board where the chip is soldered on, and that would fit in the original socket. The problem then is, that chip would not be re-programmable very easily, because the combined chip-on-adapter creates a non-standard pinout that a programmer doesn't support. You would have to make a "reverse adapter" to ever reprogram later, or get a test-clip that clips righ onto the chip on the board. I *think* it should bebpossible to make an adapter that plugs in to the original dip socket and still has a plcc socket itself, by using a surface mount plcc socket instead of a throu-hole one. There is a figtronix option rom board that uses that. I have made a few and they work. But the down-side in *that* case is that a low profile surface mount plcc socket can only be soldered with an oven or hot air and paste. It's MUCH simpler to solder the through-hole kind for the average hobbyist. I have managed it, and did it using a cheap $20 hot air gun instead of a $60-$500 "real" hot air soldering station, but it was tricky and finnicky and not reliably reproduceable. I also botched it several times and had to keep starting over. (heat it all up enough to come off, clean off all solder, and start over very carefully applying new paste and flux and trying lay the socket in exactly the right position...) No mmatter which way you turn, there is either one problem, or some other problem. Mike Stein has a board that uses a full dip chip, and can plug in to the original socket, but I don't think it can accomodate a socket to make the new, standard 27C256 removable for reprogramming and still all fit in the case. If it can, that would be the way to go. Otherwise it's just one of many equally good-with-a-problem options. Remember, this is all only for M100's that have the original non-standard pinout main rom. Some late M100's and all T102's don't have any problem and don't need any adapter. -- bkw On Aug 23, 2017 5:18 PM, "Gary Weber" <g...@web8201.com> wrote: > Hello all, > > I have a question for anyone out there who has created a main ROM adapter > for their Model 100, using these parts and following these instructions: > http://tandy.wiki/FigTronix#Model_100_Main_ROM_27C256_PLCC_Adapter > > My question has to do with this statement: > "Unfortunately, using this adapter requires desoldering the original > socket from the motherboard. It IS possible to do this, without damaging > either the motherboard or even the old socket, with flux, solder wick, and > patience." > > I'm a little confused as to why the original socket would have to be > de-soldered. Can't this adapter just be plugged into an empty CPU socket? > Or is it the case that the M100 case can't close again because of something > so high in that socket pressing against the keyboard circuit-board? > > Thanks for the info! > > > -- > Gary Weber > g...@web8201.com >
