IBM 5100 find

User avatar
inmbolmie

19 Jan 2020, 23:01

This is a recent awesome "barn find". An IBM 5100 with its matching IBM 5103 printer. At last a laptop with a proper keyboard! but you will need a very strong lap by the way as this thing weights some 23Kg :? . The printer is simillary weighted.

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It is a spanish machine, but the only localized parts are the front panel switch legends, that is a good thing because localized Beam Spring keycaps are usually of a lower quality than the standard keycaps. It is a 32K RAM and BASIC only machine. With 32K the 5100 cost about $13.000 in its day or $62.000 adjusted for inflation. No idea of the printer cost but I imagine it was also substantial.

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Has very nice "nuclear white" keycaps with BASIC sublegends. A few of them have scratches and some stems are bent, but nothing terrible. Contamination shield is disintegrated but no evidence of rust whatsoever, contrary to other Beam Spring keyboards the top plate seems to be made of aluminium, so not even a single trace of rust is visible from the top. Keyfeel is great, even by Beam Spring standard, the sound is very bassy as could be expected with the keyboard mounted in such a massive metal chassis.

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The good news is that it seems to be almost complete, rust free and only lacking two keys (CMD and left shift) and the BASIC reference card. It came also with a rotten storage tape I doubt I can get anything from.

The bad news is that the working status is unknown after so many years badly stored. I will take some time checking the AC wiring, power supply, capacitors etc. before proper testing can begin. If anything important is broken inside I will have a very bad time fixing it.

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To be continued if anything interesting comes from the restoration.

User avatar
SneakyRobb
THINK

19 Jan 2020, 23:07

Wow! Top tier. NICE FIND. Looking forward to this!

Very interesting that top aluminium plate. I wonder if the fact it was portable meant they tried to save weight, notwithstanding that 24kg size

User avatar
Bass

20 Jan 2020, 00:18

That 5100 of yours looks to be in pretty good shape considering it's a barn house find. I suggest wearing gloves when you begin your restoration as the foam underneath the card cage will most likely have turned into a nasty puddle of tar that can be very difficult to wash off.

Good luck on the restoration. A few others here (snuci and I) have also found and restored some 5100's but were unable to get them working. The ROS cards are especially prone to failure, so it would indeed be very impressive if you can get yours to work!

User avatar
Redmaus
Gotta start somewhere

20 Jan 2020, 05:52

where can I find these "barns" lol

also great find

User avatar
Chyros

20 Jan 2020, 08:03

Wow, great find mate, congratulations! :D 23 kg, damn, that's more than I thought it would be xD .

mcmaxmcmc

20 Jan 2020, 11:55

el psy congroo

Nice find! Hopefully you can find some spare caps for the missing keys there.

User avatar
inmbolmie

20 Jan 2020, 12:24

mcmaxmcmc wrote:
20 Jan 2020, 11:55
el psy congroo

Nice find! Hopefully you can find some spare caps for the missing keys there.
For the missing keycaps I've thought about making reproductions. The left shift is easy as it is the same as the right shift. For the "CMD" I think it is the same mould than the 5251 "Enter" key but rotated 180 degrees, I have to take some measurements to check that.

andrewjoy

20 Jan 2020, 12:27

That is amazing. That thing is just built to insane standards, we simply do not get anything made to that standard any more.

John Doe

20 Jan 2020, 13:06

Is there any other stuff found to share in the gold barn?

User avatar
inmbolmie

20 Jan 2020, 13:18

John Doe wrote:
20 Jan 2020, 13:06
Is there any other stuff found to share in the gold barn?
Yes it is, I got a few other things, being the 5100 by far the most interesting, but I need some time to process that because now I have a problem of lack of space at home...

User avatar
inmbolmie

21 Jan 2020, 17:24

Bass wrote:
20 Jan 2020, 00:18
That 5100 of yours looks to be in pretty good shape considering it's a barn house find. I suggest wearing gloves when you begin your restoration as the foam underneath the card cage will most likely have turned into a nasty puddle of tar that can be very difficult to wash off.

Good luck on the restoration. A few others here (snuci and I) have also found and restored some 5100's but were unable to get them working. The ROS cards are especially prone to failure, so it would indeed be very impressive if you can get yours to work!
As you said it seems there is something wrong and it points to the ROS board. I've checked the AC circuits, power supply, display connections, buses, etc, everything is OK but doesn't boot. In this site the author explains that booting the machine halted with the SHOW REGISTERS mode enabled you should see in the screen the contents of the first 512 bytes of executable ROS like this:

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But in my case I can see only this:

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I'll investigate a bit deeper into the issue. That keyboard deserves a second opportunity.

User avatar
inmbolmie

24 Jan 2020, 22:26

Bass wrote:
20 Jan 2020, 00:18
That 5100 of yours looks to be in pretty good shape considering it's a barn house find. I suggest wearing gloves when you begin your restoration as the foam underneath the card cage will most likely have turned into a nasty puddle of tar that can be very difficult to wash off.

Good luck on the restoration. A few others here (snuci and I) have also found and restored some 5100's but were unable to get them working. The ROS cards are especially prone to failure, so it would indeed be very impressive if you can get yours to work!
Well, after all it wasn't the ROS the bad component causing the issues. The screen capture with supposedly ROS data that I post wasn't really the right one, the correct is this:

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Trying to find a logic behind this to give me a clue of the problem I realized that what I was watching was the last column of the first module of correct ROS data repeated over every prior column. So that suggested a problem with the addressing of ROS data. I revised the schematics and tested some signals over the board and isolated the problem over the data address bus in the display controller card.

Then finally detected the real problem: Someone tinkering inside the computer prior to me left this blue jumper cable broken:

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This should be connecting to ground one pin of the address generator circuit but the cable was broken inside and making no contact. I didn't detect this with the prior visual inspection because the cable was in place with no evident signs of being broken, and with so many cables lying around. After fixing this...

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Now I had the correct ROS data over the screen, so the ROS was OK. Then after activating the RUN switch...

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Finally got some text! Apparently the self-checking routine detected a keyboard error, stuck keys. Touched some of the randomly to try to unstuck them, and after another reset...

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The BASIC prompt, so... It works! But the keyboard doesn't. So now It's time for some keyboard action :mrgreen: .

User avatar
ZedTheMan

24 Jan 2020, 22:39

Oh man, it's like the entirety of the thread before this was just foreplay, haha.

User avatar
Bass

24 Jan 2020, 23:16

Congrats man! I could be wrong but I don't think you'll have much trouble diagnosing your keyboard problem unless there is physical damage somewhere. It's quite easy to remove from the rest of the machine and can then be disassembled just like any other beamspring.

User avatar
inmbolmie

27 Jan 2020, 20:35

Let's get to it. First some images in its original unrestored state.

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Closeup of the spacebar stabilizer, the only part clearly rusted.

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Keys

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One weird thing is that the back plate is made of plastic instead of metal. It's like after committing to a zinc-cast chassis for the computer they suddenly developed some kind of weight-consciousness when finally adding the keyboard.

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Keycaps off!

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Derusting bath for the spacebar stabilicer.

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Now we go for the creepy part, there is a ton of grime inside this thing. It's unbeliebable how good this keyboard feels giving the amount of crap that it has inside.

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Closeup over THAT FOAM.

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Holy crap!!!! What's THAT THING inside the keyboard :shock: . It looks to me like some kind of alien microscopic civilization from planet Krypton. This is when I started worrying and got some gloves and masks for the rest of the restoration.

After annihilating the poor things, the worst part came, removing that yellow residue took an entire can of glue remover and 3 hours of scrubbing.

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Now the switches, there was only 3 casualties, one bent stem, one dislodged flyplate and one broken slider arm. All easily fixed. The broken slider was fixed with some superglue.

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Final result for the cleaned parts.

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Two of the switches were black instead of grey, so it seems they were replacement parts but were otherwise indistinguishable.

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Cutting some new foam.

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One thing I wasn't aware of, it seems that this particular beam spring has a symmetrical stem. Here compared with a regular sloped stem.

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The aluminium top plate is pretty light, weighting only 220 grams.

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The keyboard with switches in place. I applied some PTFE dry lube to the sliders for extra smoothness.

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The whole assembly without caps weights only 1,32 Kg. Or approx. two and a half apple aluminum keyboards in Standard Chyros Units (SCU).

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Testing it before putting keycaps in, everything working now.

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Posing next to a distant relative.

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The space where the keyboard goes inside the case.

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Keyboard installed and working.

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Next step will be creating reproductions for the missing keycaps. This is going to take some time because It's a first for me.

And also try to make the tape unit work. When I started with this project I thought that I would have for sure to replace the DC motor rubber band... But why using a DC motor and rubber band when you can use an AC motor and a frikkin' transmision belt?

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This thing is definitively built like a truck.

User avatar
SneakyRobb
THINK

27 Jan 2020, 21:42

Aluminium barrel plate, plastic backplate. Very interesting. That foam does look like some kind of moss collection as well. That plate is actually quite aesthetic tbh. Well done.
inmbolmie wrote:
27 Jan 2020, 20:35

The keyboard with switches in place. I applied some PTFE dry lube to the sliders for extra smoothness.

The whole assembly without caps weights only 1,32 Kg. Or approx. two and a half apple aluminum keyboards in Standard Chyros Units (SCU).
Absolute madman lubricating beamsprings!

That weight is Actually shocking.

User avatar
AJM

27 Jan 2020, 22:07

Fascinating! Thanks for the documentation.

manisteinn

27 Jan 2020, 23:27

Great find and nice detailed pictures!

I've modeled, printed and resin cast beamspring caps so I could potentially help you out with that, here are some thoughts:

I assume both your shift keys have identical stem placements, is that right?
I'd happily cast a copy for you for the cost of materials, but I only have the 3278 and Selectric sets so you'd have to send it. There's of course the risk of it getting lost in transit, I'm not sure I'd do it myself. Perhaps you could find someone local to do a 1:1 copy.
I could use my non-stepped 1.25 and 1.5u shift keys, but those would leave a gap and wouldn't be a great match.
A selectric 2u shift is probably the closest, the edges could be filed to 1.75u.

Is the CMD key unique to this series? I'd think a flipped 5251/displaywriter return key would be the closest fit but I don't have any of those either. If anyone does and is ok with sending it I'd happily cast a copy of it.

I recently made resin copies of SLA prints which turned out great, that's also an option for prints based on 3d scanned or modeled originals.
I don't have any real experience with the durability and longevity of more expensive SLA/SLS prints but my cheap ones yellowed significantly within a year, resin casting also allows for closer color matching.

Hope this helps

User avatar
inmbolmie

28 Jan 2020, 21:05

manisteinn wrote:
27 Jan 2020, 23:27

I'd happily cast a copy for you for the cost of materials, but I only have the 3278 and Selectric sets so you'd have to send it [...]
Thanks for your support, I have been for some time thinking about trying to cast some keycaps and this is one good opportunity so I think I will try first myself. I'm reading now some posts here and there looking for "inspiration".
manisteinn wrote:
27 Jan 2020, 23:27

I assume both your shift keys have identical stem placements, is that right? [...]

Is the CMD key unique to this series? I'd think a flipped 5251/displaywriter return key would be the closest fit but I don't have any of those either. [...]
With regard to the shift key...

Foto 28-1-20 20 34 34.jpg
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Luckily it has a double-mount so It can work as left or right shift indistinctively.


And about the 5251 Return...

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It fits, but I think it has the wrong slopes, changed between upper and lower part. But it just works and will be good enough to use it as a mold.

manisteinn wrote:
27 Jan 2020, 23:27


I've modeled, printed and resin cast beamspring caps


Very nice keycaps by the way, with these I only aspire to "fill the gap" because I know no matter how hard I try the new keycaps won't ever look original.

manisteinn

28 Jan 2020, 22:27

inmbolmie wrote:
28 Jan 2020, 21:05

Thanks for your support, I have been for some time thinking about trying to cast some keycaps and this is one good opportunity so I think I will try first myself. I'm reading now some posts here and there looking for "inspiration".
Nice, it's quite fun :)

Feel free to ask if you want any tips. I'll mention that the stem shape being so deep and narrow makes the bottom mold fragile, there's quite some pulling force required when demolding and a loud pop when the vacuum finally breaks. Both of mine got progressively looser and eventually ripped (last picture)
It's not a big deal if you're just doing a couple of caps though, and you can of course reinsert the original keycap in the intact top mold and just repour the bottom.

For future molds I'm planning to try out metal stem inserts for improved consistency and longevity.
inmbolmie wrote:
28 Jan 2020, 21:05


With regard to the shift key...

Foto 28-1-20 20 34 34.jpg

Luckily it has a double-mount so It can work as left or right shift indistinctively.
Interesting, the selectric 2u key also has a similar stem pattern
inmbolmie wrote:
28 Jan 2020, 21:05
And about the 5251 Return...

Foto 28-1-20 20 36 29.jpg

It fits, but I think it has the wrong slopes, changed between upper and lower part. But it just works and will be good enough to use it as a mold.
Great! You already have one :)

I figured it'd be the wrong profile, you should be able to get much closer to the original by filing the bottom surface to the correct angle.

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