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IBM Model M membrane mapping / tracing

Posted: 17 Feb 2022, 17:50
by vzsozs
Hello, I have made a crude drawing of the traces on my Model M so you can use it for repairs or debugging or to make your own, which I would if I could find thin electric tape.
model m membrane map1+2.png
model m membrane map1+2.png (1.2 MiB) Viewed 2741 times
model m membrane map 1.png
model m membrane map 1.png (742.01 KiB) Viewed 2741 times
model m membrane map 2.png
model m membrane map 2.png (790.88 KiB) Viewed 2741 times

Re: IBM Model M membrane mapping / tracing

Posted: 17 Feb 2022, 17:58
by sharktastica
Very nice work, these should come in handy!

Should also point out that these should be applicable to ISO Enhanced Keyboards (and terminal versions of both) too AFAIK. For up to and including third-gen 10x keyboards (ie, ones with Triomate 16 + 8 or 16 + 12 (the 4 extra being for the lock-lights) membrane connectors), IBM seemed to have stayed true to one membrane matrix design. Hence why it's easy to convert ANSI to ISO and vice versa. The only major exception would be the Erase-Eaze 10x, M5 and M13 keyboards Lexmark introduced (one extra position for the normally unused barrel left to the spacebar barrel), but those aren't common at all.

Re: IBM Model M membrane mapping / tracing

Posted: 17 Feb 2022, 18:07
by vzsozs
Thanks sharktastica, you can see with the black empty circles, that there is technically a trace there, but in the ANSI layout it is not used and in the plate there is a spacer instead. I have not tried this but my guess is that if you take out the spaces and put in a button with a spring it will work as a ISO layout. Even in the numpad area you could insert 1u keys instead of the enter and + keys, and assign some custom function in MSKLC.

Re: IBM Model M membrane mapping / tracing

Posted: 17 Feb 2022, 18:14
by sharktastica
Doh, I missed the fact they were empty circles. But yes, if you put buckling springs on those ISO positions, it should just work (after you've changed your OS's language as well). For the split + key area, the extra key is used in terminal layouts and should also return a scancode by default, but I'm not sure what it is off the top of my head.

Re: IBM Model M membrane mapping / tracing

Posted: 18 Feb 2022, 11:03
by Muirium
Cool, a much prettier version of Phosphorglow's similar matrix work. I'll link to this one (for fullsize at least) from now on. ;)