Inside an Atari TT 030 keyboard

[arapineau]

I have this board I needed to clean up for a while now. It’s an Atari TT 030 keyboard with an AZERTY layout.
Beside being dirty, the keyboard seems to sink in the frame and there is some sort of rattling song when you shake it.

For those who are interested, the TT 030 was a Motorola 68030 based workstation class computer Atari released in the early 90s mainly for the European industrial market,
Germany being his prime target. It came out with TOS 3 operating system but could also uses multiple variations of UNIX. Also it is fully compatible with the Atari MegaST keyboard.

The lighting doesn’t make justice to the level of grime and yellowing this keyboard is in.
It’s not terrible because I made a very quick surface cleaning when I got it, but it’s certainly dirty and yellow.




The key caps are made of ABS and the lettering is printed.




The lettering seems to be sort of marine blue but looking at the less yellowed caps, it seems it was more on the greenish side (once cleaned).



But what lies under the caps? Doom! Well no, actually it’s more like Mitsumi hybrid switches…



… and there are of multiple kinds too D:



I kinda start to feel like it will be a better time investment to roast demons on the summit of Mt. Erebus rather than cleaning this mess.




Anyway, let’s flip it and admire his feet before cracking the case open.



Just three screws and we are in, one of them in under the warranty sticker.




So inside there is a board module in which the switches reside. This module is wired to a PCB with two ribbon cables and a ground wire on one of the connector for the mouse and joystick.




There is also these little buggers running free inside the case.



That explains the noise I heard while shaking the board, I hope it’s more the result of someone sitting on it rather than a mechanical default resulting of a bad design, and that some epoxy will be able to fix that for good.
Two of those stands are broken on the back panel and on on the top one.




And here is the kind of cable and connector this board uses.




The PCB




sports electrolytic capacitors with unmarked polarity D:



Those have to go, I’ll need to order some solid replacement parts.
Right now I have Nichicon parts I could use to replace one of them but I don’t want to put components that will eventually leak inside, and using Nichicon caps in a Mitsumi hybrid keyboard sounds like wasting food to me.

Meanwhile, let’s take apart the key module







and remove the sliders to clean everything thoroughly.



And apparently the plastic was made in May 1990






(don’t mind the ALPS black leave springs)






Beside the cable I can’t do much without the new capacitors.



So, more latter.

[Findecanor]

Interesting that it has a curved backplane. All other keyboards I have seen with those switches have had a flat backplane: PC keyboards and Mitsumi-made Amiga keyboards.

The Mega ST keyboard has Cherry MX switches. I think the majority of Atari ST keyboards I have had Silitek dome with slider.
Cool that there is a mouse/joystick port on each side. The integrated computers have the DE9 ports on the bottom of the keyboard where they are really hard to reach.

[arapineau]

Interesting that it has a curved backplane. All other keyboards I have seen with those switches have had a flat backplane: PC keyboards and Mitsumi-made Amiga keyboards.

Well I don't know. I think they are Mitsumi hybrid but I could be wrong, though the probability is pretty low since Mitsumi made the backpanel.
But once again, there are multiple Mitsumi switches and I can't tell which type they are.

The Mega ST keyboard has Cherry MX switches. I think the majority of Atari ST keyboards I have had Silitek dome with slider.
Cool that there is a mouse/joystick port on each side. The integrated computers have the DE9 ports on the bottom of the keyboard where they are really hard to reach.

I have no idea about the switches used in the Atari Falcon though.

The extra ports were also present on the MegaST keyboard but in a more frustrating position, but please don't remind me about the internal ports on the STf/STe.
I don't know what was worst: the fact they were on the side of the original ST, or they that they added 2 enhanced 15 pins joystick ports on the left side of the STe that could be used with standard ST joysticks but no adapter were provided.

The thing that bugs me is how they managed to provide the bandwidth for basically three devices on just 4 wires.
I wonder if there is analog or logical multiplexing in the keyboard, or if they used some sort of different protocol between the computer and the keyboard and the controller inside does some translation job.

[Findecanor]

I wonder if there is analog or logical multiplexing in the keyboard, or if they used some sort of different protocol between the computer and the keyboard and the controller inside does some translation job.

Yeah, there is a microcontroller on the keyboard which talks a serial protocol with the host computer.
Back in the day, I got a book on programming the ST (although I never ventured outside BASIC), and it described the protocol.

I think it was pretty smart of the designers to make the microcontroller read both the keyboard and the mouse and joystick. It gives you daisy-chained devices like on the Mac but keeping the hardware relatively simple.
ADB and PS/2 needed complex logic in the mouse and the Amiga used one of its custom chips for the mouse.

[arapineau]

I wonder if there is analog or logical multiplexing in the keyboard, or if they used some sort of different protocol between the computer and the keyboard and the controller inside does some translation job.

Yeah, there is a microcontroller on the keyboard which talks a serial protocol with the host computer.
Back in the day, I got a book on programming the ST (although I never ventured outside BASIC), and it described the protocol.

I think it was pretty smart of the designers to make the microcontroller read both the keyboard and the mouse and joystick. It gives you daisy-chained devices like on the Mac but keeping the hardware relatively simple.
ADB and PS/2 needed complex logic in the mouse and the Amiga used one of its custom chips for the mouse.

To be honest everything about the ST was smart, from using CPLD for the glue logic to buying out of spec Motorola serial controllers for dirt cheap.
It's sad that nowadays all you can see about it are bashing video game contests against the Amiga 500, and how everyone seem to have forgotten what a great computer it was at the time.

[arapineau]

Here is the finished recaped PCB back in place (although I forgot to resolder the ground wire when I took the picture and had to remove the PCB again in order to fix that)



And here is the final result



Now I guess I'll have to recap the TT too

[Findecanor]

It's sad that nowadays all you can see about it are bashing video game contests against the Amiga 500, and how everyone seem to have forgotten what a great computer it was at the time.

Well.. Not without its flaws. The first low-spec models of the Atari ST had no integrated floppy drive. Probably because Jack Tramiel so much wanted to beat his rivals back at Commodore at pricing.
But yes, I'd say that the ST's engineers were clever. I heard that the MIDI ports had been added pretty much by the engineers themselves, and the MIDI market accounted for a whole lot of sales of the system as a result.

I had an Atari 520 STe and then a late-revision Amiga 500 (actually, I still have both) and the Amiga was definitely an upgrade IMHO. AmigaOS was way better than anything else at the time, and the ST struggled with side-scrolling games because it did not have hardware support for it. (I'm not sure how much the Mega ST and STe's blitter would have helped).

[rpiguy9907]

The curved backplate was common and used on Commodore Colt/PC10/PC20 keyboards. Also any Mitsumi PC Keyboard of the era also had the curved backplate (EQ-99Y models).

Like the Atari, my Commodore PC keyboard also had two different color buckling rubber sleeves. Light green on the keys and a stiffer dark green on the spacebar. Pictures attached.

One stem was broken so I swapped it with a stem from a broken C128 keyboard, the KQs are 100% compatible with the linear KRs used in Amigas and the C128.