If you can forgive somewhat blurry pictures, there has been another little bit of progress. Something I have wanted for a while has finally gone from theory to drawing board to reality. One reason for the rev. 2 ROM module was to allow programming of the flash ICs without having to do any soldering. I have now managed to assemble all of the parts and do some initial testing, and it seems to work as intended.
For the curious, this is the revised ROM module (yes, this one was hacked together without the proper pin headers):
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You may have already seen my parallel-port flash programmer board (pictured previously), but there is now another accessory: an adaptor that allows a ROM module to be directly plugged in for programming. That looks like this:
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That allowed another test: I assembled another ROM module, with 2 2 MiB flash ICs, programmed them using the adaptor, and am now listening to MIDI playback using a 4 MiB ROM set (with obligatory paranoid stares to watch for sparks or magic smoke). So far, it's not bad at all. The increased capacity also means that I could include an SBOS chunk in the ROM, so I will be able to do some testing of SBOS and company in the near future.