Converting an IBM 5120 Beamspring to USB

[koalapear]

Hey guys, I picked up an old IBM 5120 terminal for free off of craigslist a while back. Unfortunately the terminal was nonfunctional but I was able to salvage the keyboard out of it! Free beamspring yay!






Quite the monster!

Only problem is it doesn't use the same controller setup as other beamsprings and as such is unable to use an Xwhatsit controller in its current state.

















I had a couple ideas as to how to get this thing working with a modern computer. First would be to create my own converter that would utilize the existing controller. I was able to find the pinout for the connector in the IBM service manual. This is pretty far over my head however and sounds like it would be a lot of work. Here's a link to the service manual: ftp://ftp.informatik.uni-stuttgart.de/p ... 0192-0.pdf Pertinent info on pages 2-72 through 2-76.

My other idea was to simply create a new PCB that would be compatible with Xwhatsit's controller. This seems like the easiest way to go to me but I've never designed a PCB before. It seems pretty straight forward for conventional contact switches but the capacitive magic that makes these tick is beyond me.

I would really appreciate any insight as to how I might go about making a converter or designing a new PCB so I can actually put this beauty to use!

Also, all it seems to need besides USB compatibility and maybe a fancy custom case is new foam. The stuff that's in there has turned all sticky and the keys all wobble around. I would assume the foam that most use for Model Fs from McMaster Carr would work but I'm not sure. Any suggestions on what type of foam would be best would be awesome!

Thanks!

[andrewjoy]

From the photo it looks as if you could tap into the lines you need and install an xwhatsit. You would need to get busy with the multimeter .

[koalapear]

From the photo it looks as if you could tap into the lines you need and install an xwhatsit. You would need to get busy with the multimeter .

I thought that might be a possibility as well. The way things are routed and the chips at the bottom of the board made it seem like this matrix might be set up differently though. Here's a link to the full album of the PCB: http://imgur.com/a/0glsD

[snuci]

If you want to sell some parts, PM me. I wouldn't mind a set of the cards and backplane, just in case. Nice find. These things are so heavy, people just give them away and that is sad.

Forgot to add, let me know how you make out. If it's non-destructive, I'd love to try out whatever solution you come up with.

[koalapear]

If you want to sell some parts, PM me. I wouldn't mind a set of the cards and backplane, just in case. Nice find. These things are so heavy, people just give them away and that is sad.

Damn, I wish I could. My parents got tired of it sitting around and tossed it while I was away

I wasn't too happy about that as you might imagine. All I have left now is the keyboard...

[snuci]

If you want to sell some parts, PM me. I wouldn't mind a set of the cards and backplane, just in case. Nice find. These things are so heavy, people just give them away and that is sad.

Damn, I wish I could. My parents got tired of it sitting around and tossed it while I was away

I wasn't too happy about that as you might imagine. All I have left now is the keyboard...

That's too bad. If you took it apart, you might have been able to get it to work. The cards often slide out and reseating them will get it going again. As you know, it was a tank

[koalapear]

If you want to sell some parts, PM me. I wouldn't mind a set of the cards and backplane, just in case. Nice find. These things are so heavy, people just give them away and that is sad.

Damn, I wish I could. My parents got tired of it sitting around and tossed it while I was away

I wasn't too happy about that as you might imagine. All I have left now is the keyboard...

That's too bad. If you took it apart, you might have been able to get it to work. The cards often slide out and reseating them will get it going again. As you know, it was a tank

I did give fixing it a go. Took out all the cards and blew everything out with compressed air and reseated everything but it was a no go

It didn't help that all the foam in the card box had all turned to googey tar either! Too many years of sitting in the Arizona heat I imagine.

I didn't really know where to go from there so it ended up sitting in the garage for months until it met its demise.

[tigpha]

Looking at the schematics on page 255 of the friendly manual you linked to, in section "Keyboard -- Z4 Socket Pin Assignments" I smell a hint of the same sort of protocol as for the the IBM 5291 terminal keyboard. There's a "Kbd Strobe" and eight "Kbd 1...7" lines too. I suspect the "Kbd O" or "Kbd P" might be the the data-out line. Have a look at the Bigfoot with Arduino forum topic. I think you may be able to resurrect this beauty with very little modification.

[snuci]

The foam turns to gooey tar no matter where it is That's the first thing I do with these old machines. Same as foam pads in foam and foil keyboards (casually bringing the conversation back to keyboards).

[koalapear]

Looking at the schematics on page 255 of the friendly manual you linked to, in section "Keyboard -- Z4 Socket Pin Assignments" I smell a hint of the same sort of protocol as for the the IBM 5291 terminal keyboard. There's a "Kbd Strobe" and eight "Kbd 1...7" lines too. I suspect the "Kbd O" or "Kbd P" might be the the data-out line. Have a look at the Bigfoot with Arduino forum topic. I think you may be able to resurrect this beauty with very little modification.

Thanks for the tip! I'll have a good read through that thread

[koalapear]

Looking at the schematics on page 255 of the friendly manual you linked to, in section "Keyboard -- Z4 Socket Pin Assignments" I smell a hint of the same sort of protocol as for the the IBM 5291 terminal keyboard. There's a "Kbd Strobe" and eight "Kbd 1...7" lines too. I suspect the "Kbd O" or "Kbd P" might be the the data-out line. Have a look at the Bigfoot with Arduino forum topic. I think you may be able to resurrect this beauty with very little modification.

After some reading it looks like you're right. It seems to have the same sort of I/O setup as the Bigfoot except for the power pins. It appears to need +5V and +8.5V. I'm not sure how I'd go about supplying that 8.5V. Perhaps use something like this? http://www.amazon.com/SUNKEE-LM2577-Adj ... B008HMETBE

I'm also not sure what the Power on Reset and +Typematic pins are for.

[pr0ximity]

Did it have a solenoid in the case? Might explain the 8.5V

[koalapear]

Did it have a solenoid in the case? Might explain the 8.5V

I don't recall seeing anything resembling a solenoid. The area of the case around the keyboard was completely empty, besides the keyboard assembly of course. If there was one it would have to have been mounted elsewhere which doesn't make much sense. The solenoids run off 9V which indeed makes one wonder if that's why this has the 8.5V line but I would think if it's the solenoid that needs that 8.5V then why was it being supplied to the keyboard and not the solenoid itself?

[lot_lizard]

Did it have a solenoid in the case? Might explain the 8.5V

Almost has to be. The other beamsprings would be the same voltage for their solenoid (and it is a very odd voltage for anything else). I'm assuming you have already looked at this, but if you haven't... It would be a great starting read for this project. You'll notice a very similar step-up converter for the solenoid controller in xWhatsit's work

http://downloads.cornall.co/ibm-capsens ... e-usb.html

I'm also not sure what the Power on Reset and +Typematic pins are for

Typamatic is essentially typewriter character repeat. I would assume the value was stored in a separate controller, and retrieved as requested (mechanically, vs through software like you would expect a computer to behave). This is a time when "smart" typewriters and computers were merging, and if the technology existed already for the typewriter, worry about making the software solution later (a guess). In any case, it sounds like something you would be able to omit

[JP!]

Any luck on this project?