I don't have an original M100, however, I've made in the past some ROMs adapters for other old computers, they are actually smaller than the original (EP)ROM, I usually use SMD EEPROMs on a PCB board and Batten & Allen side pins (or straight ones when I feel like spending more time soldering them. The problem nowadays is sourcing the right EEPROM chips. They can be programmed easily with a simple socket adapter on your favourite programmer. HTH Frank IZ8DWF
On Thu, Aug 24, 2017 at 10:29 AM, Brian White <[email protected]> wrote: > I think there's another stupid simple possibility that I keep forgetting to > check too: maybe there is room if the board is just offset a little to one > side or another? > > Or, maybe have the new chip laying upside down on that nice empty bare spot > right next to the original socket. > The adapter board would be the size of two dip28 next to each other. > One dip28 footprint has pins. > The other has a socket, both on the same side of the board. > If that works, then it looks funny, but you have everything. > * original socket left alone, "damage-free-towing" > * new chip is socketed and removable from the adapter > * adapter is removable from the motherboard > * original rom can be put back in any time. > > The pins for the original socket might need to be slightly tall. > The entire board might need a little securing, like velcro or double sided > foam between the new rom and the bare spot of the motherboard. Even if the > socket is actually stiff enough to hold it all just fine, you probably want > something anyway to ensure the new rom doesn't knock on the motherboard and > cuase wear on the spot where it rests over time. > > > On Thu, Aug 24, 2017 at 2:22 AM, Mike Stein <[email protected]> wrote: >> >> >> ----- Original Message ----- >> From: "John Gardner" <[email protected]> >> To: <[email protected]> >> Sent: Wednesday, August 23, 2017 8:52 PM >> Subject: Re: [M100] Figtronix Main ROM adapter >> >> >> > ...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... >> ----------- >> The price of an IC socket; same board... >> >> It's been quite a while; between Steve and myself we managed to lose some >> notes and it's not well documented, but one of the four jumper positions is >> to allow (re)programming; there's a default trace for 'normal' operation >> without jumpers that has to be cut. >> >> I'll have to revisit it one of these days... >> >> I thought about redoing it with larger holes that would take machined >> socket pins for a lower profile socket but it didn't seem worth while. >> >> And of course there's this version: >> >> >> http://www.club100.org/memfiles/index.php?action=downloadfile&filename=m100y2k.pdf&directory=Steve%20Adolph&; >> >> m >> >> ===================================> >> >> >> >> >> > >> > 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] >> >>> >> >> > >
