...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...
A pgming adapter sounds doable - And cheap... On 8/23/17, Brian White <[email protected]> wrote: > 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" <[email protected]> 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 >> [email protected] >> >
