@retrocomputing
z80 *NMI is hard-coded to call address 0x0066. This is the middle of the default FCB in CP/M. Can't really use it in CP/M itself, but a user program is free to set up a vector in the FCB, so the *NMI switch is at least potentially useful.
The #Teletek front panel isn't a full front panel.
It's 8x 8-sement LEDS (2 rows of 4)
An 8-segment LED bar graph (8 individual LEDs in a row)
A switch wired to *NMI (crash the machine switch)
A speaker
Spent a few hours on this s100 card last night. This is the front panel controller for my #teletek.
I was mainly trying to figure out why its responding to disk controller writes, but the wiring seems ok...
Mostly i was trying to figure out how the speaker output is wired up... if i did that right, it needs a DtoA and still wouldn't work? I don't know op-amp wiring...
I'm still amazed at how few rs232 line I use these days. The coco and the teletek have serial lines to my server, and of course the teletek has a serial line to its terminal. A free connection for the m100 and wp2 and that's it! Everything else is wifi or ethernet.
I pulled the LED controller board out of my #Teletek #systemaster #s100 machine. I think the comparator chip has failed? Anyway it was responding to writes of all the IO addresses. Very distracting. And it made me worry that it was going to mess up the signals.
So my CP/M machine now seems fully operational again! Woot!
secsolution
Willard Goosey