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Disable D888 undo feature by modifying the firmware?

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Joined: 23 May 2011
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PostPosted: Mon Dec 19, 2011 1:41 pm    Post subject: Disable D888 undo feature by modifying the firmware? Reply with quote

The undo feature on the D888 is known to be really annoying and disrupting of workflow. While there are ways to record without the unit going into "Working..." mode, it would be best to disable the undo feature completely. I asked Korg for assistance but they do not disclose much information about the internal workings of the machine.

Being a computer programmer, I figure it might be possible to modify the firmware so the unit does not go into "Working..." mode after recording. The way a wave file is laid out on disk means that if you want to insert sound at the beginning, you must append all previous audio to the end of the new segment, effectively a full copy of the whole file. However on the D888 we are not inserting at the beginning, but recording over the previous data. But being a non-destructive (undo) feature, new data is recorded to a temporary file. The old file is renamed TRK01VT01.UND then the TRK01VT01.TMP is probably copied into TRK01VT01.WAV and overshooting audio from old file appended to wave file.

Large file copying operations on slow hardware takes time (the D888 is afaik based on Analog Devices Blackfin ADSP-BF532 400MHz processor). So the best thing would be to disable any such copying feature. I would suggest recording inplace, overwriting any previous audio data. That would eliminate the need for any renaming, copying and appending. If you record a segment in the middle of a song, the data would be written to the middle of the wave file, leaving wave data before and after intact. No undo would be available. There are a few possible ways to achieve this:

1. Korg would read this message, and released a new firmware. (should not take their programmer more than a few hours)

2. Someone had the sourcecode (presumably written i C) and rewrote the routines.

3. Someone had knowledge of Blackfin processors, incl. ide controller a simulator and a debugger and reverse engineered/located the routines responsible for delays. E.g using VisualDSP++ tools from Analog Devices.

4. (most likely, least scientific) Hex edit / hack the D888SYS.BIN into forgetting about the undo feature. One possible hack is to edit references to .UND and .TMP so they all point to the .WAV file. That might null out some renaming/copying operations. However it will probably have severe side-effects, (for which I take no responsibility). Another way is to insert JMP and RET opcodes in the right places(provided you actually read macine code).

If anyone has ideas or useful info about these issues, or is willing to guineapig(and possibly brick) their D888 go right ahead. Here is what I have so far:


D888 Service Manual

Home of ADSP-BF532 from Analog Devices

greets from tetsuoii in tromsø, norway
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Joined: 07 Feb 2020
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PostPosted: Fri Feb 07, 2020 4:26 am    Post subject: Disable Undo? Reply with quote

How is it that you can record without enabling the undo feature? Sorry for the decade-later response.
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