@all, i am very sad :-(, the adress line decryption looks good for SC55 ROM 's, i am shure, that data line decryption is also good. Loaded the dectypted 3 files stored as one file is now clearly listable - instruments are now recognizeable - and i can hear, that adress-lines are fine. But useing the …

Hi mattw, great work, thank you so much, but NewRisingSun is right when he pointed out, the work is far from done. Next steps would be to uncover SC55 Control-ROM wave-form coefficients, as well as parameters for the LFO (frequency, pitch) and others. Detuning, chorus and other params must yet found …

@NewRisingSun 😀 very great work. Lifting a 30 year old secret. Can't believe.

You do not have much time yeah, but even weaker hardware like CM-32P that we know for sure how it works (MAME has full emulation of it) is fast enough to handle both address and data (de)scrambling. However, if @NewRisingSun is right, then data scrambling for SC55 is 20-bit compared to 19-bit for …

you are absolutely right, yes it would be faculty of 8! but there are still 4 bits in addition to the 12 bits. What still is a "black hole" is the order of the 3 bytes that you menasured. if we assume, that bytes are hard-wired scrambled, than the "middle byte" (2 nibbles) are also scrambled in the …

@mattw, thank you so much for these further li nks and informations. I 100 % agree to your statements. But I have build a rompler synth based on SC55 sf2. with an UC3A512 Microcontroller. And what can i say about it, is, that things are very time-critical, especialy in therms of number of voices. …

The waveform roms are 8 bit. So even if SC55 uses 12 bit of sample, the additional 4 bits (to 12 bits) doesn't come from the same rom chip. maybe, I am misunderstanding you, but one possible explanation for that is what I mentioned few times before, i.e. how 12-bit data are encoded in 8-bit inside …

Unfortunately NewRisingSun adress-decryption works perfectly on SC55 SF rom-chips but doesnt't work on SC88 soundfont. One of the the reason would be, if we take a look on both service-notes schematics (SC55 & SC88), that in schematic of SC88 the adress lines are mixed up per se. My SC88 is in …

Big news (at least to me, maybe it was done in the past, but I am not aware of it - if you know, let me know, to prevent me reinventing the wheel): So, I was able to decrypt small portion of the Sound bank from ROM dump from real SC-55 hardware device! Yes, only "small portion" for the moment, …

kitrinx and I made some substantial progress on the SC-55 wave ROM front. We have successfully understood the process of address scrambling . kitrinx connected a logic analyzer to log the address fetch patterns when playing a single piano note. It looked like this (identation mine): 60455 70B20 …

I really don't know with VSC the "pcm data address map" is so obvious: 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0a 0x0b 0x0c 0x0d 0x0e 0x0f ------------------------------------------------------------------------------- 0x78 0x00 0x00 0x00 0x00 0x00 0x67 0x35 0x92 0x06 0x00 0x24 0xDC …

Usually, each sample comes along with a root key and a range around that root key for which the sample is mapped to specific notes. The list of samples then make up the complete keyboard mapping. The range can be expressed in different ways, like lower and upper key or really a range around a note …

@jonas-fr: next problem would be, to get the entry-point addresses as well the looping-start, looping-end point addresses for every sample. these addresses are for my opinion stored in the firmware-ROM. At least only an approximation could by done for the TVF's and TVA's. I guess, that the CPU ( …

Owner of a SC-55 here, I want to shrink down my setup (486 computer hooked to a SC-55 via MIDI) while retaining the SC-55 abilities. I'm currently focusing on getting a 1:1 copy of the SC-55 soundfont (I won't go in the debate between what's the closest soundfont today ,there's some very good clone …