On Friday, October 4, 2013 9:00:27 PM UTC-5, Brian Marstella wrote:
If there's interest, I was going to try to keep the project as "clean" as possible from the start and probably post a few update notices here.
From memory its a SIO with a simple hardware modem. If you add two optoisolators, two (maybe three) resistors in place of the modem, and stick a different clock on it for the uart, it turns into a MIDI interface, given some connectors of course and some peculiar division ratios in the UART. May as well put pads on the PCB for that. This kind of project has been on my infinite list of things to do so although I have the motivation I don't know when/if I'll have the time.
If you can keep a 30kbaud pipe full then by definition you can play any midi file. I was thinking more of sound effects rather than full musical songs. Or what amounts to a CPM based drum machine. Or the CPM machine could respond to MIDI from a music keyboard, although I have no idea what to have the CPM machine do in response.
There's an infinite number of fun things to do with a dedicated SIO like put in a header to drop a TTL-serial-level GPS on with a remote antenna; this could be a fairly accurate way to set the RTC. And about a hundred other interesting serial peripherals at both 3.3V-serial, 5V-serial, and RS232 level serial voltages. Serial LCD displays, and serial servo controllers, serial bluetooth interfaces, Insteon/X10 home automation interfaces, who knows what else. If you put the pads on to hold optional cassette modem, RS-232, 5V TTL, 3.3V TTL, maybe RS-485, people will find a way to use it, I'm sure. Serial IO universal application board you could call it. Its just a couple extra pcb pads, if you have the space.