DCC730 software versions

From the repair bulletin:

  1. MODEL: DCC730

  2. SYMPTOM: Introduction of software USER 034

  3. CURE: Introduction of software USER 034 - Improved software USER 034 is available as programmed OTP and can be ordered with service code 4822 900 10716. In comparison with software USER 032, the following complaints will be solved: - DCC is freezed by amplifier when DCC is searching from STOP or winding (should not be freezed). - TIMER PLAY on ACC: DCC always goes to TRACK 1 (should play from current position). - TIMER PLAY/RECORD with DCC awake and tray open: tray stays open (should close). - TIMER PLAY with superuser-tape and current tracknumber unknown: DCC starts playing from TRACK 1 (should play from current position). - TIMER PLAY on ACC: DCC doesn’t wake up. - TIMER RECORD: DCC doesn’t start recording. - CLEAN HEAD INDICATION

That means that the excessive Clean Head message is in fact a bug on an older version of the microcontroller.

@Jac Do you know anything about this?

It seems possible to dump the ROM by glitching and program similar chips with it to solder them in. But as the problems are only very minor it is near the bottom of my priorities.

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Do you know this for a fact?

So far, I’ve assumed that it’s not possible to dump the NEC 78K microcontroller ROM. I tried to find resources online such as compilers too but it seems to be non-existent unless you’re a big company with lots of money, so that’s why I’m using the “Locutus” approach that I explained in my presentation last year: put the main CPU to sleep and take over the bus.

Once I know enough, it might be possible to replace the entire CPU by something else but that would be a lot of work. If it’s possible to reuse what’s already there by dumping the ROM and disassembling the code, it might save some time.

=== Jac

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No, but great progress was made in the direction in the last years with projects like the ChipWhisperer. In fact, dumping could be easier than disassembling and reusing on something else.