The daunting task of toggling in a program of any significant length into a SCELBI has made me consider ways of automating the process, at least for demonstration purposes. What I’m looking at, is altering the program on one of my PS/2 to ASCII keyboard adapters and connecting it to the SCELBI’s front panel connections. Here are the reasons why I think this will work out really well.
The front panel is controlled through TTL I/O lines pulled up to +5 volts with 1k resistors. This is something that the AVR should be able interface directly to.
There are more than enough I/Os available on the PS/2 card, especially if I repurpose the three configuration jumpers. There are 8 bits for data and three pushbuttons for control. In addition I should be able to tap into a couple of the CPU status lines in order synchronize with the CPU states.
I already have both keyboard and RS232 drivers written for this board.
The keyboard can be used for control and the RS232 port to get data from a host computer.
An alternate approach is to use RS232 for both data and control.
I have plenty of these boards available. I’ve used less then half of the lifetime supply that I had made when the Mimeo first came out.
The interesting thing about this little board, is that I can also use it for other interface applications on the SCELBI, at least until I have time to reproduce authentic 70s era interfaces that were available. Examples include:
RS232 interface
With a bit of extra hardware – cassette tape interface
