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 <mhs.st...@gmail.com> wrote: > > ----- Original Message ----- > From: "John Gardner" <gof...@gmail.com> > To: <m...@bitchin100.com> > 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 <bw.al...@gmail.com> 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" <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 > >>> > >> >
