Differentiating IBM 3101, 3270 & 5250 Model B/Model F/Model M keyboards

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sharktastica

28 Jan 2023, 12:37

Earlier this week, I made an IBM keyboard ID guide aimed at terminal keyboards of the 3101, 3270 and 5250 compatible families! The goal was to satisfy some requests I got on how to identify what family of terminal a given keyboard belonged to. I've also seen a few examples of mid-'80s and '90s terminals of one family paired with keyboards from another. Thus, I thought this would be a good thing to cover!

Link: https://sharktastica.co.uk/topics/3101-3270-5250_diffs

I state tips on how to spot the differences between 3101, 3270 and 5250 keyboards, which is generally easy/obvious for the earlier beam spring keyboards but less so for later Model F and Model M keyboards. For those, I break down how you can tell each family apart by the layout of the navigation cluster and the numeric keypad. I'll summarise a TLDR below, but the page linked above will provide more background and cover a lot more nuance in the later sections.

Feedback is of course appreciated!

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Summary
The IBM 3101 ASCII Display System, 3270 Information Display System and 5250 Information Display System were three major product families that originated in the 1970s that possessed many terminals from the '70s, '80s and '90s. Compatible/emulating terminals, thin clients and software are still available today, and thus some IBM-compatible terminal keyboards are still under production via Unicomp. I talk about three self-defined 'eras' of IBM terminal keyboards under these families.

Model B(eam spring) era
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The original terminals of each family used beam spring keyboards. Thankfully, IBM introduced unique keyboard designs for each, thus they're easily recognisable and my page doesn't dwell on them for too long. They can be identified by a combination of their overall shape, the columns of separated keys on the left, and [if applicable] if their keypad is joined to the alphanumeric keys. The fact they're so unique is probably a major reason why people in the community generally refer to beam spring keyboards by their terminal type numbers (like "3101" and [imprecisely] "3276" and "3278") instead of generic names like "F122" or "unsaver" for Model Fs.

"Early" Model F era
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When Model F was introduced, it seemed the practice of a unique keyboard design per terminal would be continued. The IBMs 3104, 3178 and 5291/5292 seemed to portray this. Although as evidenced by the low-profile keyboard replacement for IBM 3101, shared assembly design was already being toyed with. Still, I point out an obvious way to ID each.

"Late" Model F/Model M era
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The introduction of the 104-key Model F ("unsaver") in March 1983 and 122-key Model F in October 1983 planted the seeds of a new paradigm where the keyboard assemblies for many different terminals would now be shared, with only what's printed on the keycaps changing. The introduction of the Model M Enhanced Keyboard and 122-key Model M in 1985 only bolstered this, and the current 3270 and 5250 keyboard offerings from Unicomp still reflect this. One keyboard design can take on many functional layouts. As such, I spend a bit more time detailing how to differentiate them apart.
  • By what's printed on the back (an obvious one, but literally searching up a part number should give you an answer)
  • By "navigation cluster" layout
  • By numeric keypad layout
Example comparisons:
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num_pad.png
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Last edited by sharktastica on 28 Jan 2023, 16:55, edited 1 time in total.

User avatar
sharktastica

28 Jan 2023, 12:43

On another note, I'm also trying to make this info (terminal family per applicable keyboard) easier to find on my website. My Keyboard Part Number Database now has a "Known Host Systems" field that will list a given keyboard's possible hosts and provide a photo of said host. At the moment, this field is not filled out for most of my database's entries but I'm working to backport it to all the existing part numbers. I think I have 1,500 keyboards left to go through...
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In the near future, I'll be debuting a page dedicated to terminals. Providing key facts, a photo (if available) and an expandable list of known keyboards. Here's a preview of the WIP page. I anticipate launching in Q2 this year.
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paperWasp

28 Jan 2023, 22:06

Great reading! Thanks for putting in your time on it.

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dcopellino

29 Jan 2023, 12:26

I looked upon your post with great interest and I think that's the way to classify correctly our beloved vintage input devices.

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Weezer

15 Feb 2023, 14:15

If you're going to do this there should probably be greater differentiation in the 3270 section. The 3270 in the photo is actually a keyboard from a 8775 terminal.

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sharktastica

15 Feb 2023, 16:34

Weezer wrote:
15 Feb 2023, 14:15
If you're going to do this there should probably be greater differentiation in the 3270 section.
I'll add an additional photo to the summary soon. However the article itself makes this clear, showing both 'generations' of 3270 family Model Bs and a [bolded] suggestion for quick identification for either. I could probably go into more detail but I think what's already there is easy to remember and does the job.
Weezer wrote:
15 Feb 2023, 14:15
The 3270 in the photo is actually a keyboard from a 8775 terminal.
It may have well shipped with 8775s, but I've seen no indication that it was exclusive to 8775. I'm aware 8775 share 3270 keyboard designs, but the keyboard in the summary photo is P/N 1745709 and is in fact an RPQ (8K0932, EBCDIC typewriter keyboard with tab key and numlock) and is referenced in 327X-centric documents like the 3276/3278 Parts Catalog (S126-0029-0) and various announcements like 183-032 and 184-017. I just confirmed with the keyboard's owner that it even came with an IBM 3278 Problem Determination Guide in its palmrest. As I've said in other threads, nothing is clear-cut with IBM. Nuances, nuances everywhere. Anyway, it serves its purpose of demonstrating what a typical [late] 3270 family (which includes 8775s, 3270 data over serial and partitioning support) Model B keyboard looks like.
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Falkenroth

16 Feb 2023, 06:54

Thank you for taking the time to do this.

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