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Raven
April 29th, 2010, 06:25 AM
I've been assuming that the 5160 *and* 5150 came with the 83-key (forgive me if it's 84, I constantly get that mixed up) XT "IBM Personal Computer" keyboard - until now. I learned that the latest 5160s ended up with the enhanced keyboard like the XT-286 shipped with. I looked at my AT keyboard and it's labeled "IBM Personal Computer AT". I started to wonder if the exact keyboard that shipped with the earlier 5160s should say "IBM Personal Computer XT" like the badge on the front of the machine, or if the 5160 and 5150 did indeed share a keyboard model and I've got the correct one matched up to my 5160 already.

Old Thrashbarg
April 29th, 2010, 10:10 AM
I'm not quite clear on what you're asking, but here's what I know about the XT keyboards... it's probably not all-encompassing of the different options, but FWIW:

The usual keyboard for the 5150 and 5160 was the 83-key model, I don't know if the badge was different for the two, but the keyboards are otherwise identical for the two models.

There was an 84-key model, which came with the AT. It looked similar to the XT keyboard, except it had status LEDs and the keypad was shifted a bit, separated from the rest of the keys. That board doesn't work on an XT.

Then there was the 101-key Model-M type "enhanced" board. There were a few different variants of that one... of course the common PS/2 version, but also an AT version, which was basically the same as the PS/2 one except with a 5-pin DIN connector, and finally an XT version, which had a black cord and a blank spot where the status LEDs would normally be. Again, the XT and AT versions of that keyboard are not compatible, although I think there may have been a switchable one that could do both.

Raven
April 29th, 2010, 11:25 AM
The XT version of the Model M with the AT connector is actually auto-sensing and does both AT and XT signals. The one without the LEDs that is - it came with the XT-286 and very late XT models. I have one of these, love it (saved it from out in the rain ^^).

The basic question was indeed whether there's a specially badged "Personal Computer XT" keyboard, or if they both just say "Personal Computer".

Old Thrashbarg
April 29th, 2010, 11:33 AM
I wanna say that they were all labelled "IBM Personal Computer." I'm 95% sure the one I have is from an XT, but it only says "Personal Computer" on the badge, and I can't remember ever seeing one that said "XT" on it (at least, not an actual IBM keyboard).

per
April 29th, 2010, 12:00 PM
Both of mine 83-key keyboards just says "Personal Computer", and there is no doubt they came originally with my XTs.

I will guess it doesn't say XT because both the 5150 and 5160 used the exact same keyboard interface, and problably therefore the same keyboards.

Raven
April 29th, 2010, 12:18 PM
I wanna say that they were all labelled "IBM Personal Computer." I'm 95% sure the one I have is from an XT, but it only says "Personal Computer" on the badge, and I can't remember ever seeing one that said "XT" on it (at least, not an actual IBM keyboard).


Both of mine 83-key keyboards just says "Personal Computer", and there is no doubt they came originally with my XTs.

I will guess it doesn't say XT because both the 5150 and 5160 used the exact same keyboard interface, and problably therefore the same keyboards.

This is what I thought, I just wanted to make sure I wasn't missing a keyboard in my collection to go with my XT better. ;)

Thanks.

per
April 29th, 2010, 12:32 PM
This is what I thought, I just wanted to make sure I wasn't missing a keyboard in my collection to go with my XT better. ;)

Thanks.

They did however make two revisions of the 83-key keyboard, one using tri-stated buffers, the other using open-collector buffers. The XT uses open-collector buffers for the keyboard port, so the revision 2 keyboard would be the best match then. However, it practically doesn't matter since both revisions will function correctly.

Raven
April 29th, 2010, 05:20 PM
I assume that that means on an open-collector buffer you can type for a bit and the keyboard will hold the information (up to a certain point) until the machine is ready for more input? If so I've got that model.

k2x4b524[
April 29th, 2010, 08:07 PM
the ones with the LEDs are autosensing aswell, just when they are used in an XT, you can't use the LEDs

per
April 29th, 2010, 10:59 PM
I assume that that means on an open-collector buffer you can type for a bit and the keyboard will hold the information (up to a certain point) until the machine is ready for more input? If so I've got that model.

It's not even that much difference. The only difference is what solution is used when controlling the data/clock line in the keyboard interface.

Open collector is quite obivous. If only one of the outputs to the line goes low, the entire line goes low (like if all the inputs to the line is connected together in a big AND-gate). As said, this solution is used on the XT and the type 2 keyboard. You can identify a type 2 keyboard in that it uses 74LS07 buffers.

The tristate solution is not standard use of tristate. The lines are high on default, and all the tristate-buffers have grounded inputs. The actual signal is connected to the /enable lines of those buffers, so if all signals on a line is high, the line is default high because all the buffers are tristated, but if only one signal goes low, the line is grounded. This has the same effect as the open-collector solution, but I would guess the power-consumption is slightly different. This solution is used in the original PC and in type 1 keyboards. You can identify a type 1 keyboard in that it uses 74LS125 buffers.

modem7
April 29th, 2010, 11:55 PM
the ones with the LEDs are autosensing aswell, just when they are used in an XT, you can't use the LEDs
The subject of IBM auto-sensing keyboards has been discussed at least once before in these forums. I'm positive that it came out in those discussions that only some of the enhanced keyboard models could auto-switch.

Raven
April 30th, 2010, 04:04 PM
Well mine can, and I'm quite glad it can - heh. :)

My PS/2 Model M cannot run in XT mode, but I don't know that you guys have been including the PS/2 models when referring to them in this thread.

Perhaps it would be good to add a page in the wiki to test and track which models are capable of both modes?