My brother is onto msx (and older computing) homebrew things and I wonder time to time to maybe research a bit to maybe try tomfind a solution but everytime I start to dig I can’t just avoid ending at “why not just bypass the whole memory system and attach an iPhone with koala sampler (or even a raspi which supports koala btw) and get the best of two worlds” so keeping the ADCDAC side, fx, even synth but just use the midi side and then some hardware hacking about in and outs (so output of mic/line + fx into usb soundcard in plug to koala and the out plug into sp where the signal was hijacked so it goes to the master and sp outputs again…?)
Maybe it could be possible understand the whole hot swappable Atapi drive but for 4 stereo polyphony? About the 4 track recorder maybe it could be possible add some vstudio parts… I will love to see a solution but with propietary file compression without sources it requires a bit (too much) working for so little reward (imo) and in the end these are nutty expensive due the madness about lofi (we called noise back in the day…) and all the sp series… now revamped by roland themselves with 404mk2. I dunno… maybe just try to ask at retrobrew computers club groups so maybe one of these genius gets it as a challenge and crack the weird firmware inside these or just replace the cpu by raspi and emulation of that part at the brain surgery I’m pointing. It should not be impossible but worthy? I should look again into schematic to see how hard it will be but it’s like dejavu… I feel I done it but what I found made me brainwhased just to avoid the pain over and over… #FuckURolandcorporates I hate them as time goes more and more!