An SMD EEPROM would certainly work, but many folks are still uneasy about DIY SMD; you'd also still need an adapter although you might already have one with your programmer.
Lots of options, but I'm biased (and I've got a bunch of 27xxx's ;-) m ----- Original Message ----- From: "Francesco Messineo" <[email protected]> To: <[email protected]> Sent: Thursday, August 24, 2017 4:34 AM Subject: Re: [M100] Figtronix Main ROM adapter >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] >>> >>> >>> >> >> >>
