megatronicthronbanks, 22 days ago

@tubetime Probly waaaay too late to ask, but a video of the restoration progress would rock. Love that stuff.

tubetime, 22 days ago

this basically means i'm buried in IBM schematics that use a totally weird representation of logic gates.

tubetime, 22 days ago

this particular version of the 729 has a whole bank of SMS cards -- IBM's Standard Modular System which uses germanium transistors. these came out before their (equally odd) SLT cards and modules.

tubetime, 22 days ago

here is one of the cards. this one is an "MH" card containing 4 PNP driver transistors.

tubetime, 22 days ago

if anyone wants to see the back of the card, it looks like this.

tubetime, 22 days ago

i want to build a breakout system to make it easier to test these cards. they use a 16-pin connector with 0.125" spacing between contacts. at the local electronics store, i could only find this 44-pin connector.

tubetime, 22 days ago

my idea is to remove a few pins and cut the connector down.

tubetime, 22 days ago

the final product. you can barely see the glue seam. bonus points to anyone who knows why the connector pin alphabet is missing a few letters. further bonus points to anyone who knows why each contact has two wires connected to it.

cr1901, 22 days ago

@tubetime I and O too easy to confuse with 1 and 0?

I feel like I've seen this before in e.g. Game Genie codes.

MLE_online, 22 days ago

@tubetime I have a front panel from some old electronic device that has the same letters removed

kwf, 22 days ago

@MLE_online @tubetime I O S and Z are really numbers in disguise

orion3311, 22 days ago

@tubetime the missing letters can be mistaken for numbers!

root42, 22 days ago

@tubetime that one transistor doesn't look healthy...

masukomi, 21 days ago

@tubetime i’m having trouble with the fact that this is so chunky looking that I feel like it could just be a standard breadboard

Dhmspector, 22 days ago

@tubetime was this the IBM equiv of DEC’s FlipChip modules?

original_peterm, 22 days ago

@tubetime All the logic pages were printed on a line printer (1403 etc). There was a special character set for the job.