Vintage IBM keyboard (Personal Computer 5150) sends computer to a halt
December 16, 2013 9:01 AM   Subscribe

I have recently acquired the keyboard for the IBM 5150 Personal Computer. It also came with a DIN-5 to PS/2 adapter, so I plugged into my desktop, and everything screeched to a halt -- typing occurred very delayed from the key presses, mouse became inoperable. Is this the keyboard, the adapter, some software incompatibility, or something else completely?

My desktop runs Windows 7, in case it's an OS thing. Weirdly enough, pressing ctrl+alt+del to choose the task manager would instead go to the lock screen/switch user/log off/change password/task manager screen, and then automatically go back to the desktop, then go back to the lock screen/switch user/etc., screen, then go back to the desktop. Even after I unplugged the keyboard and put in my old keyboard, the machine kept cycling through that process.

(It is possible that the keyboard or adapter may be malfunctional, as my boyfriend got it for me off the internet. I can probably ask for more info about how much he paid, what the seller described the quality as, etc., Would there be a way for me to know whether the problem is software, hardware, etc.,? The keyboard shows the same problems on my boyfriend's Windows 7 desktop, but that doesn't seem to rule out any of the possibilities.)
posted by subversiveasset to Computers & Internet (9 answers total)
PS/2 ports aren't hot-swappable - they date back to the days when you had to restart a computer for hardware changes to take effect. Try rebooting with the keyboard plugged in from the start and see if that works for you.
posted by Tomorrowful at 9:03 AM on December 16, 2013

I'm surprised anything happened-- definitely reboot with the keyboard connected. You can leave your (I presume) USB keyboard connected.
posted by Sunburnt at 9:27 AM on December 16, 2013

Response by poster: Tomorrowful,

Unfortunately, there is no actual text response at all on a reboot. Although, if it helps, if I just turn off the computer (without properly shutting down, so that the "reboot in safe mode" screen comes up), pressing any key will turn off the automatic restart timer (although, unfortunately, I can't actually select any options.) So the computer is recognizing something... Just not doing anything with it.

plugging in the keyboard without restarting reminded me of another thing that happens with the keyboard : random beeps from the computer. These beeps do not happen on a reboot.
posted by subversiveasset at 9:28 AM on December 16, 2013

Best answer: Although they have the same physical DIN connectors, the IBM PC keyboard uses different keycodes than the IBM AT which is the direct ancestor of modern keyboards.. You need to get a special adaptor to make it work with a modern computer.
posted by RonButNotStupid at 9:29 AM on December 16, 2013 [2 favorites]

Best answer: PS/2 ports aren't hotswappable but most people treat them as they are, since usually it doesn't matter. The IBM keyboards tend to draw more power than your average $3 cheapie, though, so you should not do that with a full-on IBM keyboard (or anything relatively nice - usually it doesn't matter but yes they are not designed for that). For what it's worth, people who sell Model Ms and such tend to also sell "high-draw" PS/2-to-USB adapters because some of the cheaper ones don't provide enough power for the keyboard to work.

However: is this a for-real, pre-Model M IBM keyboard? As in, intended to be used on a for-real IBM PC or PC/XT? (Like maybe a IBM Model F 83-key keyboard?) If so, and if the adapter you have is a simple just-a-cable adapter, what you've done is confuse the hell out of both the keyboard and the computer. The pre-PC/AT keyboards used a totally different protocol to communicate with the computer. (Third-party keyboards of the era typically had a little switch on them to set them in to XT or AT mode.) Hagstrom Electronics makes an adapter you can use for this: it's $54.95. The ClickyKeyboards people (who sell almost exclusively refurbished Model Ms and such) recommend them. Again, if you have a pre-Model M keyboard and your adapter doesn't look like the Hagstrom unit, then you've just got a simple adapter that will not work with your keyboard.

If it's a Model M or something like that, then you may have either a dodgy adapter or a bad PS/2 port. The ClickyKeyboards people who i've liked to do sell adapters and PS/2-to-USB adapters that will work with the older IBM keyboards, so you might try that.
posted by mrg at 9:29 AM on December 16, 2013 [1 favorite]

Response by poster: Sunburnt,

I guess my message to Tomorrowful should have also included a message to you. Should have clicked preview...


If that's the case, then I definitely think I would need a different adapter...


I think that it is some sort of Model F, based on looking at the models on the Deskthority IBM Model F keyboard page and seeing that it looks closest to the Personal Computer has Personal Computer on the name.

I was thrown off because it seems to have a F number key guide for Lotus 1-2-3 Release 2.2 dated for 1989, but this appears just to be a card, so when I remove that, the keyboard looks exactly like the 5150 Personal Computer Model F.

Here is a picture of the full keyboard, a picture that shows the logo, and a picture of the connector with the [I'm guessing, wrong?] adapter.
posted by subversiveasset at 10:03 AM on December 16, 2013

Those keyboards were rated for 100 Million keystrokes, which would outlast Leo Tolstoy or George R.R. Martin, so I wouldn't let the Lotus 123 date throw you; this keyboard is almost certainly the last surviving component of the XT it shipped with.

Unicomp sells genuine (new) Model M boards, and variations thereon, as well as replacement parts-- $80-$120, from my quick glance, for new boards. They aren't the original maker of Model M, but they are the licensed maker since '96.

Not sure if they offer service, but maybe they can meet your needs one way or another.
posted by Sunburnt at 11:28 AM on December 16, 2013

IIRC, older IBM PC and XT keyboards had the keyboard controller built into the keyboard, while on the AT, PS/2, and newer systems, the keyboard controller is built into the motherboard. It may be that there is sort of a "doubling up" issue with the two keyboard controllers conflicting with each other.

Old PC and XT keyboards use different keyboard scan codes than the newer AT and PS/2 keyboards.

There may be a PC/XT / AT selector switch on the underside of the keyboard, maybe under a cover?
posted by xedrik at 12:06 PM on December 16, 2013

there won't be a selector switch on a for-real IBM board; they just didn't ship PC/XT keyboards with AT or PS/2 systems. evidently if you pop the bottom cover off (looks like just the two screws there) you may be able to find a label that will positively identify it. see the pics here (down towards the bottom, around the 3rd from last).

also, on edit, yeah, that cable isn't going to work. you need the Hagstrom one or some equivalent (of which I don't know if there are any).
posted by mrg at 4:50 PM on December 16, 2013

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