Don't forget that you can address 32bit memory and the final machine will likely have several MB of memory as standard.
Its 12bit colour at the moment but isn't that changing for HDMI? 320x200x256 image display is beyond the 64kB limitation too but the aim is to do it easily.
I wasn't really serious about 24bit DACs... I realise that is a bit out there.
The Amiga did 12bit samples and 4 channels, right? The M65 _should_ be better than that?
I guess 4MB is only going to get you a minute and a half of uncompressed audio at 22050Hz and 16bit. But it could be streamed from the SDCard which could be several GB. In any case, even 1MB of data could be quite a large number of samples if each sample is only 1 or 2 seconds. Its the final mix quality that I'm concerned about, if you want to mix them to have multiple channels.
I wonder if the CPU would be able to handle something like OGG or FLAC (purely integer) decoding? I'm guessing something would be possible.
Meh... I guess I'll have to live with what Paul decides.
I also have some ideas for improving the SID which I should pass by Paul... I'd like to see it have sine, "reversed" saw and "super saw" waveforms, too. Maybe another noise type (the SID noise is rather pink instead of purely white). I think its possible if you replace the noise+other waveform settings which currently produce no output. Having those would greatly reduce the need for sampled instruments.
Anyway, that's another topic.