Fixing a 30-year-old Roland synthesizer bug
1–10 of 37 posts
Re: Fixing a 30-year-old Roland synthesizer bug
#2This is cool, so TL;DR: The 3rd gen run of a Roland early digital synth product had an unresolved timing issue causing pitch playback problems. Recently, investigation revealed they hadn’t accounted for an Intel MCU part sub. The spec indicated the sub part was running too fast. They downclocked it via crystal swap which destroyed the unit’s MIDI timing. So they located the control ROM instructions to modify to fix the resulting MIDI sync issue and burned a new one:
0x1A8D: 1D5Fh -> 1388h
0x215C: 17h -> 0Fh
0x216D: 1D5Fh -> 1388h
I spent some time inside an early Roland sampler of this era during the pandemic. It’s really well engineered stuff that sounds great.
Re: Fixing a 30-year-old Roland synthesizer bug
#3Awesome work! I love the care and attention that people put into understanding these devices.
I'm currently in the middle of a vintage synthesiser hacking project as well. Last year I made a fully annotated disassembly of the Yamaha DX7 firmware, and did some other technical analysis of the synth. Since then, I've been waiting for a chance to put this knowledge to good use. I found a DX9 on a local trading site, and I'm in the process of hacking its firmware to remove the 4-operator restriction that made it such an unpopular synth.
Re: Fixing a 30-year-old Roland synthesizer bug
#4The Kawai K5 I used to have was also 8096 based.
Re: Fixing a 30-year-old Roland synthesizer bug
#5The Kawai K5 I used to have was also 8096 based.
Intel 8097 in the Roland W30, and I think also the S50.
Re: Fixing a 30-year-old Roland synthesizer bug
#6This is cool, so TL;DR: The 3rd gen run of a Roland early digital synth product had an unresolved timing issue causing pitch playback problems. Recently, investigation revealed they hadn’t accounted for an Intel MCU part sub. The spec indicated the sub part was running too fast. They downclocked it via crystal swap which destroyed the unit’s MIDI timing. So they located the control ROM instructions to modify to fix t…
I guess it makes sense that it would be a common divider ratio (5000) but $1388 leapt out at me from disassembling the Ensoniq Mirage firmware.
Re: Fixing a 30-year-old Roland synthesizer bug
#7This is cool, so TL;DR: The 3rd gen run of a Roland early digital synth product had an unresolved timing issue causing pitch playback problems. Recently, investigation revealed they hadn’t accounted for an Intel MCU part sub. The spec indicated the sub part was running too fast. They downclocked it via crystal swap which destroyed the unit’s MIDI timing. So they located the control ROM instructions to modify to fix t…
This reminds me of the binary patching done in The Martian film.
Re: Fixing a 30-year-old Roland synthesizer bug
#8The Kawai K5 I used to have was also 8096 based.
Didn’t know that: hard to believe they managed to pull off additive synthesis on an 8096. That’s impressive
I had a later Kawai K5000 which added short PCM samples for attack transients. That thing was crazy, foolishly gave it away more than a decade ago
Re: Fixing a 30-year-old Roland synthesizer bug
#9The Kawai K5 I used to have was also 8096 based.
Didn’t know that: hard to believe they managed to pull off additive synthesis on an 8096. That’s impressive I had a later Kawai K5000 which added short PCM samples for attack transients. That thing was crazy, foolishly gave it away more than a decade ago
I received a final software update from Kawai and had to open it to install the EPROMs, which is how I saw it. It was a very cool synth - very high quality feeling.
Re: Fixing a 30-year-old Roland synthesizer bug
#10This is cool, so TL;DR: The 3rd gen run of a Roland early digital synth product had an unresolved timing issue causing pitch playback problems. Recently, investigation revealed they hadn’t accounted for an Intel MCU part sub. The spec indicated the sub part was running too fast. They downclocked it via crystal swap which destroyed the unit’s MIDI timing. So they located the control ROM instructions to modify to fix t…
I guess it makes sense that it would be a common divider ratio (5000) but $1388 leapt out at me from disassembling the Ensoniq Mirage firmware.
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