Adapt ST Keyboard for TT

My TT keyboard had some non-working keys due to broken trace line on the Mylar. I could have got a Eiffel and use a PS2 mouse & keyboard replacement. But that just kills the feeling of using an Atari. Adapting the mushy ST keyboard to be useable on the TT preserves somewhat the feeling of using an Atari. Unfortunately, there are no information on the web to do this. Luckily the Atari Forums are still alive and helpful. I hope this documentation here will be helpful to others trying to do the same. Thanks to PPera for providing the circuit information. The TT keyboard uses the same Intelligent Keyboard chip as the ST series. So all the data lines on ST are available on the TT. However there are several difference

• 1. There is no HDD activity light data line on the TT.

  2. The TT keyboard is auto-reseting on power-on whereas the ST keyboard needs a reset on the reset line.

We can ignore the HDD activity light as it is already on the TT chassis. However, we need to provide a reset for the ST keyboard so that it can start working correctly. Unfortunately, the TT does not provide this from it's keyboard output. The reset signal is a low voltage for around 20-30 ms and the normaly non-reset mode is +5V.