PDA

View Full Version : A curious 5150 / keyboard question



Floppies_only
May 13th, 2010, 07:27 PM
Hi Gang,

I thought I was getting a model 5162 off of ebay. The picture showed that type of case and two half height floppies in the left bay. But no, it's actually a 5150, original IBM PC. I never knew that they put half-height drives in them. It also has a blank plate in front of the right drive bay, which is neat to have. Another funny thing about this machine is that it only has one bank of memory filled up. The seller stated it had 64K and I assumed that he'd just made a typo, omitting the "0", or that (thinking it had a hard drive that had stopped working when the CMOS battery ran down) it was going into cassette BASIC* and showing that BASIC had 65,536 bytes free.

Alas, the seller did nail me. He said the EGA card had 256K of RAM, but upon inspection the card does not have a daughter card. But that's O.K., I only paid as much as the other IBM EGA monitor that recently sold on ebay, and I was able to get an aftermarket EGA card with 256K and drivers in addition.

One other thing that came with the lot was an IBM model M keyboard, with a black cord and AT (DIN) connector, with a copywrite date of 1984 on the bottom. It has function keys on the top, no keys not found on a 101 keyboard, and the other end of the cord has a clear, telephone connector-looking thing on it. Most unusual. There is another example of one of these on ebay right now. Does anybody know if they were designed for the IBM PC/AT? Here's the link to the one on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290394330286&ssPageName=STRK:MEWAX:IT

Sean

* I recently found out that it is possible to purchase a new cassette tape recorder from several sources online. I'm sure somebody on here know the pinouts for the connector on the IBM PC if anybody has some crazy need to save programs this way. Or load them.

kishy
May 13th, 2010, 07:31 PM
That particular Model M likely is not XT (and PC) compatible. Therefore...it's AT/PS/2.

The removable cable is a standard Model M feature; they all up to a certain year in the mid 90s have it. The keyboard-side plug is called SDL. PS/2 and DIN connector cables are interchangeable.

It won't hurt anything to plug it in and see if it works with your PC, but I believe the only XT compatible Model Ms were the ones lacking LEDs entirely (and those are actually autosensing AT/XT IIRC). That is the 1390120 I believe, going from memory only. The -131 might still have the XT autosensing support but was designed for a later system (as it features LEDs).

Edit: also worth noting, every Model M has a 1984 copyright date. The date of manufacture is about 8 million times more useful and is present on the same sticker.

Floppies_only
May 13th, 2010, 07:50 PM
That particular Model M likely is not XT (and PC) compatible. Therefore...it's AT/PS/2.

The removable cable is a standard Model M feature; they all up to a certain year in the mid 90s have it. The keyboard-side plug is called SDL. PS/2 and DIN connector cables are interchangeable.

It won't hurt anything to plug it in and see if it works with your PC, but I believe the only XT compatible Model Ms were the ones lacking LEDs entirely (and those are actually autosensing AT/XT IIRC). That is the 1390120 I believe, going from memory only. The -131 might still have the XT autosensing support but was designed for a later system (as it features LEDs).

Edit: also worth noting, every Model M has a 1984 copyright date. The date of manufacture is about 8 million times more useful and is present on the same sticker.

I'll take another look and post it here. Although I have a regular 5150 keyboard (two, in fact, plus a clone that is 101 key and is switchable between PC and AT).

By the way, here is another caveat to be filed under stupid ebay tricks: "Everything works." Well, with that keyboard, I doubt he could tell :) I had figured it would be compatible with a 5162, so I never suspected.

Sean

Floppies_only
May 13th, 2010, 11:47 PM
That particular Model M likely is not XT (and PC) compatible. Therefore...it's AT/PS/2.

The removable cable is a standard Model M feature; they all up to a certain year in the mid 90s have it. The keyboard-side plug is called SDL. PS/2 and DIN connector cables are interchangeable.

It won't hurt anything to plug it in and see if it works with your PC, but I believe the only XT compatible Model Ms were the ones lacking LEDs entirely (and those are actually autosensing AT/XT IIRC). That is the 1390120 I believe, going from memory only. The -131 might still have the XT autosensing support but was designed for a later system (as it features LEDs).

Edit: also worth noting, every Model M has a 1984 copyright date. The date of manufacture is about 8 million times more useful and is present on the same sticker.

O.K., I'm at home and looking at the keyboard. It's got no L.E.D.s and the "PT?NO" is 1390120. The date is 12JUNE86. So, it probably did work with the computer, which on further examination turned out to be an XT.

The keyboard has got an increadible feel to it and I suspect the XT actually has 256K of memory, so along with it's EGA monitor it should be ideal for using WordPerfect 4.2. I got really lucky this time.

Thanks for the information. I think I should really start taking notes when I want to describe things, rather than just trying (usually with limited success) to remember all the details about a specific piece.

Oh, the keyboard has a clear cover that goes over the keys when you aren't using it.

Sean

Floppies_only
May 13th, 2010, 11:50 PM
Oh, I forgot to mention, on the bottom of this keyboard there is a grated circular hole about 1 1/2" in diameter. It looks like it could be for a piezo-electric buzzer or similar component. A mystery...

Sean

strollin
May 14th, 2010, 05:31 AM
Shouldn't be hard to tell whether it is a PC or XT since PC has 5 slots and XT has 8.

NsMn
May 14th, 2010, 05:41 AM
I think he already recognized it, as every machine should have the sticker on it...

Besides, the half-height floppies mean nothing - the last owner could've just replaced them. That's why there are also some units with 3.5" drives in them.

kishy
May 14th, 2010, 07:38 AM
There's a certain other website which a stronger focus on keyboards specifically where the mysteries of the Model M have already been figured out ages ago, including the speaker grille (that is indeed what it is). If you want to become a keyboard fanatic, prepare for dual citizenship here/there lol.

Yeah, the ebay listing that was linked to is a 131, not a 120...if you've got the 120 then you have an AT/XT autosensing keyboard. Good stuff, they aren't terribly common.

Floppies_only
May 14th, 2010, 03:43 PM
Shouldn't be hard to tell whether it is a PC or XT since PC has 5 slots and XT has 8.

I know, I know. Simple mistake. Sorry.

Sean

Floppies_only
May 16th, 2010, 02:40 AM
I think he already recognized it, as every machine should have the sticker on it...

Besides, the half-height floppies mean nothing - the last owner could've just replaced them. That's why there are also some units with 3.5" drives in them.

I could see the former owner upgrading from one full height drive to two half height drives if they did it after the full height ones stopped being available or it was just less expensive. I noticed that these half height drives on the machine have asterisks on them. They look like the DSDD external drive that IBM made for certain PS/2 models (that is always on ebay but that you can never find the drivers for), except that they are black instead of white. Does anyone know if aftermarket drive makers put the double density asterisks on their products?

Thanks,
Sean

per
May 16th, 2010, 03:22 PM
One other thing that came with the lot was an IBM model M keyboard, with a black cord and AT (DIN) connector, with a copywrite date of 1984 on the bottom. It has function keys on the top, no keys not found on a 101 keyboard, and the other end of the cord has a clear, telephone connector-looking thing on it. Most unusual. There is another example of one of these on ebay right now. Does anybody know if they were designed for the IBM PC/AT? Here's the link to the one on ebay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290394330286&ssPageName=STRK:MEWAX:IT

Sean
I guess this was actually normal for most Model M keyboards. I got a PS/2 Model M keyboard from 1991 that has a similar thelephone connector (but with a mini-DIN connector on the computer-side). Almost all Model M keyboards are copyrigthed either 1984 or 1985.

* I recently found out that it is possible to purchase a new cassette tape recorder from several sources online. I'm sure somebody on here know the pinouts for the connector on the IBM PC if anybody has some crazy need to save programs this way. Or load them.
The 5150 techref. has been scanned and availble for download on the internett for quite some time now. It contains full schematics, and information about anything you'd like to know about it (though some topics are only priefly explained).

Anonymous Coward
May 16th, 2010, 06:52 PM
Those half height floppy drives you have in your XT are the stock IBM equipment. One of the last XTs was 5160-089. I believe it came with two half height ALPs 5.25" drives, a 256-640kb motherboard, and a 101 key model M keyboard. I happen to own this myself. The hole on the bottom of the case is for securing the floppy drives. It sounds like you have yourself a pretty nice XT. The half height drives are more reliable than the full height models, the motherboard can expand all the way to 640kb without using up an ISA slot, and the model M keyboard is much better than the 83 key.

Floppies_only
May 16th, 2010, 07:05 PM
Those half height floppy drives you have in your XT are the stock IBM equipment.

Well, of course I like that answer :) Thanks. Yes, the computer inquestion does have a hole in the bottom, centered on both drive bays and about three-quarters of the way from the front to the front of the power supply.

Thanks,
Sean