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geekhack Community => Keyboards => Topic started by: fohat.digs on Thu, 29 September 2011, 19:12:51

Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: fohat.digs on Thu, 29 September 2011, 19:12:51
Since I have a disassembled Model F terminal keyboard on my work bench waiting for a Teensy adapter per Soarer instructions (thanks, man!), I am bored.

I have both F and M 122-key terminals, as shown below, with the F having the square metal IBM badge on the right and the M having the oval badge on the left.

Since I am completely satisfied with the standard Model M key layout, my only reason for modding the Model F terminal is to get the capacitive switches underneath, which from my experience with XT and AT keyboards are exquisite in feel and sound. I am OK with the assembly and having twice as many parts to clean and re-fit, I kind of like that.

My question is this:

On ebay I have seen 122-key terminals selling as Model Ms, including some with labels to that effect, with the F-style case and the square metal badge on the right. I know that 120 and 131 Ms have metal badges, but is there any chance that some of these early Model M terminals, with the earlier cases, used the capacitive switches like the Model Fs?

I know that this is a long shot, but if there are such beasts, I will have to get one. But before I waste my time and money, I figured that somebody at Geekhack probably knows, definitively.

How about it, masters? Have you ever taken one apart?


[ATTACH=CONFIG]27579[/ATTACH]


[ATTACH=CONFIG]27580[/ATTACH]


PS - yes, the Model M really is that nasty. The Model F was at least that bad on the inside, even though it looked OK outside.
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: theferenc on Thu, 29 September 2011, 19:25:53
There are many Model M 122 terminal keyboards as you've described. I actually have several, and Kishy has a pictorial comparison of them in the pictures subforum. They are definitely the M mechanism, rather than the F mechanism.

I've heard tell of a very small number of early '86 Model M terminal keyboards that were actually Model F keyboards internally, but I've never actually seen one.
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: fohat.digs on Thu, 29 September 2011, 19:47:11
Thanks for pointing that out, I had not seen those.

My F did not have the block of DIP switches at all.

I am hoping that means that I will have less trouble than you did getting up and running with the Teensy conversion.

The F mechanism is where it's at, that was my whole reason for getting into this in the first place. 84 keys are not enough, but 122 is too many. 101 is "just right"
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: Pretendo on Thu, 29 September 2011, 20:01:08
If I'm not mistaken, I think the "M" in "Model M" stood for membrane.  Wouldn't make sense for them to have made a cap-switch version.
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: fohat.digs on Thu, 29 September 2011, 20:05:06
Oh, I see. I thought that they just moved up the alphabet and skipped the failed experiments in between the "keepers"
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: Soarer on Thu, 29 September 2011, 20:16:44
Quote from: harrymoss;423753
I am hoping that means that I will have less trouble than you did getting up and running with the Teensy conversion.

A tweaked version of the firmware sems to be doing the trick so far! I'll upload it in a day or two.
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: SmallFry on Fri, 30 September 2011, 22:38:14
Ahh, the 122 Model M...wait my M looks like the square badge one exactly (click on Model M in sig) 10/17/87. What date is that F? Kishy may also be of help as he's into IBMs.
Title: IBM Model M and Model F - terminal keyboard esoteric minutiae
Post by: theferenc on Fri, 30 September 2011, 23:48:47
As I said, the 122 key Ms and Fs were very similar. Apparently the top case of an M can fit an F with only minor modification.

Basically, the form factor continued, and they just changed the guts.