Save-a-Term: Use a regular PC keyboard with an original 5251/3278 terminal

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inmbolmie

17 Dec 2022, 19:53

It has been a regular complaint from some owners of original 5251 and 3278 terminals without the matching beamspring keyboard the lack of a cheap replacement if you just want to use and enjoy the terminal. The original stuff is with a reason highly regarded and get pretty high prices well above that of the terminal itself. This situation sometimes sadly ends up with the perfectly functional but unusable terminals being trashed.

This project aims to give an alternative to those users making possible using a regular PC-like keyboard with the terminals. It is based on a modification of the TMK converter, so in fact it is compatible with pretty much anything PS/2-like as it has plenty of connectors onboard: DIN-5 for XT/AT keyboards, PS/2, and both DIN and RJ-45 connector variants for scancode 3 terminal keyboards.

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The terminal type (3278 or 5251) is automatically detected and you have a buzzer to replicate the solenoid clicker functionality and keyboard-id DIP switches for complete compatibility. This is only strictly for 5251, 3278 and close relatives, won't work with 3277, 5291, Displaywriter or others.

I won't go deep on technical details here as everything is documented on my Github repo: https://github.com/inmbolmie/Save-a-Term. There you have schematics, firmware, gerber files for PCB fabrication as well as STL files for a 3D-printed matching case.

It is easy and cheap to make it as a DIY project on a prototype board if you don't mind it to be ugly, as it is like your regular promicro TMK except for some extra cabling, a buzzer and a linear regulator. I have also some spare units so if you need one give me a touch by PM if you prefer something assembled.

User avatar
Muirium
µ

18 Dec 2022, 13:00

Love the choice of “regular” keyboard to prove this worthy project’s chops! Nice work all round. :D

As a 3278 keyboard owner, I’m curious what uses people have found for the terminals themselves. I put my beamspring through the same full workload as all my keyboards, driving a modern system just as well as a modern keyboard could (once you learn the layout) just with epic 40+ year old feel. When I do play around with my older systems, I find them so limited by lack of https support, or lack of networking entirely, etc. etc. to the point I can only really use them for nostalgia or as terminals at best. Yet the reverse: vintage keyboards on modern computers, is an age-less dream. The gloves are off. You’re entirely up to date.

Anyway, fight the good fight. The wealth of converters and the like for deeply vintage machines now is a welcome sight to see. 8-)

User avatar
Sheepless

19 Dec 2022, 13:15

Muirium wrote:
18 Dec 2022, 13:00
Love the choice of “regular” keyboard to prove this worthy project’s chops! Nice work all round. :D

As a 3278 keyboard owner, I’m curious what uses people have found for the terminals themselves. I put my beamspring through the same full workload as all my keyboards, driving a modern system just as well as a modern keyboard could (once you learn the layout) just with epic 40+ year old feel. When I do play around with my older systems, I find them so limited by lack of https support, or lack of networking entirely, etc. etc. to the point I can only really use them for nostalgia or as terminals at best. Yet the reverse: vintage keyboards on modern computers, is an age-less dream. The gloves are off. You’re entirely up to date.

Anyway, fight the good fight. The wealth of converters and the like for deeply vintage machines now is a welcome sight to see. 8-)
(Off topic)

Hilariously (in a good way), enthusiasts are still developing software for PDP-11 operating systems. Notably, Johnny Billquist has developed a TCP/IP stack for RSX-11M+ (latest version is dated 27-Nov-22). The mim.stupi.net website runs on an emulated PDP-11 (albeit not with https). shop-pdp.net is also claimed to run on a (virtual) PDP-11, and that has https.

User avatar
Bjerrk

19 Dec 2022, 13:31

Sheepless wrote:
19 Dec 2022, 13:15
Hilariously (in a good way), enthusiasts are still developing software for PDP-11 operating systems.
As far as I understand, still quite relevant?

-----
Posted from my PDP-11
(okay, that was a lie ... )

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