Homebrew BBC Micro

[Retro_Jon]

Hello all,

I recently joined this great forum and have already popped a message in the Introduction section this afty. Hi

Quick post for a bit of spot the BBC fun! I no longer own this particular computer, but just have a look at this curiosity!

I bought it in the early to mid 90's or thereabouts at a computer fair held near Hull (UK). The guys I bought it off were, from memory, into Ham radio and electronics in general. I think I bought a modified CBM 8032 off them as well. This one has obviously been created by a hobbyist with a spare BBC mainboard. I Sold it via Ebay in 2002.

It's got a Revision 3 main board, housed in an unknown case and connected to an unknow keyboard. Until very recently I thought the case was from a Tandy Color Computer MK1, but closer inspection actually shows it's not. There's no opening on the right hand side, the slope of the case is different, etc. It's similar but it's not from a Tandy - Possibly this is an aftermarket case for a single board machine such as a Compukit UK101 / Nascom, etc?

From memory, all of the keys worked correctly, including the distinctive function keys! Wish I'd taken a photo of the underside of the keyboard PCB...

So, the pics's are below - Does anyone know what the case and keyboard are from, and does anyone on here still own this unusual machine?

EDIT - Can't seem to embed images, so pics are here in this Google Pics Album: https://photos.app.goo.gl/GLr2yMSNV5gdRinWA

Jon

[Retro_Jon]

OK, I'm clearly struggling to embed images hosted on Google photo's - give me a sec to work this out...

[tom_seddon]

ITT 2020? - https://www.homecomputermuseum.nl/en/co ... /itt-2020/

It looks like an Apple II clone of some kind, at any rate. The slots in the back seem to be standard, I think for external access to the expansion cards.

--Tom

[Retro_Jon]

Hi Tom - That's definitely the donor for the case, great spot! It has the same recesses for the nameplate stickers, same slots at the back, same cut out for the power key.

Anyone able to ID the keyboard at all? I don't know how much of it was homebrew, but can spot glimpses of breadboard under there! Someone took a lot of time to get that working with the Beeb mainboard!

Jon

[baz4096]

This gave me a bit of an itch that I really had to scratch. So nearly three hours of internet research has led me to believe the keycaps at least came from maybe an ADDS serial terminal machine of some kind, for the following reasons:

• The main number keys have 5/% 6/& 7/ ' on them and in general seem to follow the usual ASCII layout

• ADDS use the wording "NEW LINE"

• The tilde key has an upwards facing arrow

• Most of the ADDS terminals also have numerical keypads which I think have been repurposed here as function keys, including the wider zero key

I've looked at period appropriate electric typewriters, other computer keyboards from the period and many other serial terminal keyboards, and ADDS were the only ones that came close. I've not found an exact match though. Several ADDS terminals look like they were sold under the NCR brand too.

[Retro_Jon]

Hi Baz4096,

Thanks very much for taking the time to look into this mystery! Sorry for the slow reply, I've been away for a short while.

The origins of that keyboard has always bugged me and I wish I'd taken more photo's before selling the machine.

I've spent many hours online trying to find a computer / terminal with that keyboard layout - and I don't even own the machine anymore! Never thought of looking at electronic typewriters, that's a very good call indeed! A reverse image search using Google has found my old machine featured on the Centre for Computing History's web page though:
http://classicacorn.computinghistory.or ... bcmod.html (scroll down!)

I agree with you, the donor keyboard / keycaps are most probably from a terminal of some type, rather than a 70's / 80's computer. The ADDS terminals are very good candidates, thanks very much for the suggestion and your detailed reasoning. I'll investigate further.

However, having looked closely again at the pictures (of the homebrew BBC), I think that the function keys are actually part of the main (green) keyboard PCB and the breadboard that can just been seen on the left of the keyboard is for either the 3 LED's or picks up the shift lock / caps lock buttons. My thinking, therefore, is that the donor would have to have also had a row of function keys. This should narrow down the search.... but alas that has not been the case!

There seem to be very few 70's / early 80's keyboards that have a row of function keys, let alone ones that are tightly grouped above the number keys. They're usually spaced away from the number key row. One exception is the Heathkit / Zenith data terminals (of which they're are a great many types), but they're not the source, just an example of something with function keys directly above the number key row:
https://en.m.wikipedia.org/wiki/File:Ze ... rminal.jpg

Then there's the Lear Siegler ADM terminals, particularly the ADM 2 version, but again, I don't think theyre right...
https://terminals-wiki.org/wiki/index.p ... _ADM-2.jpg

I'll keep on looking!

Regards,

Jon

[baz4096]

Very good points!

Looking again at the image showing the back edge of the keyboard, I've noticed something I missed first time around. There's an unused button in the top right position, adjacent to the "Up" button at the end of the function keys. Additionally, the number 'zero' at the opposite end is clearly from a numpad, but the keycap is offset on the button. Could it be likely the keyboard PCB is from one system and the keycaps from another? Also consider that the key to the left of the left shift could possibly be a manual addition - the key looks a bit wonky to me. Perhaps!

I also think the stripboard is being used for the support ICs and remapping the switch matrix to the BBC layout.

[Retro_Jon]

Excellent observation!

I hadn't noticed that the wide f0 key was offset on the switch post itself, it's therefore clearly from a num-pad as you originally suggested. So looking for keyboards with a wide switch in that particular location is a bit of a red herring!

It's highly likely then (as you say) that the PCB and key-caps are from differing systems. Perhaps half of the complete answer is in the ADDS terminal you suggested originally!

Looking at the top down photo of the keyboard (sorry, still havent worked out how to embed pictures in posts...) - The left shift key is also offset to it's switch, so it's a wide switch on a single key post - which I hadn't noticed before either.

Additionally, there's the un-used key switch on the top right of the keyboard you spotted, all resulting in a search for a keyboard of entirely different proportions! At least we know it's a keyboard with 5 rows of keys above the space bar!

Jon