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sc55mk2-ctf-patcher: A tool to modify SC-55mkII firmware to support CTF

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First post, by TheMobRules

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Just found this tool on GitHub:

https://github.com/shingo45endo/sc55mk2-ctf-patcher

According to the description it is a tool for patching the firmware of the SC-55mkII and other synths that lack Capital Tone Feedback (CTF) support to add the alternate voicings when a non-existent tone is selected as the original SC-55 does.

However, in the README it is mentioned that it has not been tested on the actual devices so I'm not sure if it even works as intended.

Has anyone given this tool a try to see if it works? I wanted to try it myself on my SC-55mkII but I need an appropriate ROM chip to burn the patched firmware and until I get it I won't be able to test this.

Reply 1 of 6, by APN_K

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Wouldn't it be possible to test using Nuked-SC55?

Reply 2 of 6, by gerwin

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APN_K wrote on 2024-09-07, 05:03:

Wouldn't it be possible to test using Nuked-SC55?

I applied this patch to a SC-55 MKII control ROM (512 kB one).
Had to upload the patcher to a remote folder on a website, because browsers refuse to run it locally (security measure).
Used default "Recommended" compatibility options for the patching.

Then with Nuked-SC55 I tested the "canyon_invalid_ch1" midi file from here:
SC-55 mkII "No Instrument" Message With canyon.mid and passport.mid

Without the patch channel 1 shows: No Instrument
With the patch channel 1 shows: Polysynth

Seems like an improvement. 😀

Last edited by gerwin on 2024-09-17, 17:32. Edited 1 time in total.

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 3 of 6, by TheMobRules

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gerwin wrote on 2024-09-17, 16:31:
I applied this patch to a SC-55 MKII control ROM (256 kB one). Had to upload the patcher to a remote folder on a website, becaus […]
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I applied this patch to a SC-55 MKII control ROM (256 kB one).
Had to upload the patcher to a remote folder on a website, because browsers refuse to run it locally (security measure).
Used default "Recommended" compatibility options for the patching.

Then with Nuked-SC55 I tested the "canyon_invalid_ch1" midi file from here:
SC-55 mkII "No Instrument" Message With canyon.mid and passport.mid

Without the patch channel 1 shows: No Instrument
With the patch channel 1 shows: Polysynth

Seems like an improvement. 😀

Very interesting! Yeah, I also had the JS error so I was going to set up a local server in order to run the patcher but didn't get around to it yet.

One thing: isn't the mkII control ROM a 512Kbit? At least on my unit the ROM chip seems to be a 27C040 clone judging by the number of pins.

Reply 5 of 6, by TheMobRules

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Yup, 4Mbit = 512KB, not KBit like I wrote in my previous post.

Anyway, now I'm tempted to get a 27C040 and try the patched control ROM on my mkII!

Reply 6 of 6, by Mrdangerous

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Sorry to necro this thread a bit. Used the patched file with the suggested testing MIDI and it seemed to make the track work properly! However, after reading up about all this CTF stuff and looking at various threads, does this patching essentially make a SC-55mk2 pretty much good to go for everything or does it now have issues associated with certain soundtracks like the SC-55mk1 v1.21 did? For example, would the games listed at the top of this post by spiffythedog now actually function WORSE thanks to the patch or would they play properly and you now also have the bonus of CTF for tracks that need it, basically having the best of both worlds? Sorry if the question has an obvious answer, I admit this whole CTF made my head spin trying to learn about it.

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