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 Couple of Fatman questions 
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Joined: Sat Apr 25, 2015 6:49 am
Posts: 3
Post Couple of Fatman questions
Hi, just thought I'd share the Fatman keyboard I built last year.

I have a couple of questions about the firmware for the Fatman. I know it has not been updated for a very long time, but if anybody has any pointers they would be much appreciated. I'm looking to disable EG retriggering for successive simultaneous note on events to facilitate legato playing (as is typical for most analogue monosynths). I've had a poke around in the source code but my assembler skills are quite limited. I would also like to change the pitch bend range to +/- 2 semitones instead of +/- 1.

Regardless, I absolutely love this instrument - the filter is superb and the oscillators sound very good.

Sun Apr 26, 2015 7:02 am

Joined: Wed Jan 01, 2014 1:36 pm
Posts: 61
Location: Toronto
Post Re: Couple of Fatman questions
Really nice looking instrument.

sorry I cant help you with your questions.

a thought. flashing eeproms is pretty easy these days, especially with hotflashing old motherboards.

would it be possible to use an eeprom instead of an eprom?


Sun Apr 26, 2015 2:00 pm

Joined: Sat Apr 25, 2015 6:49 am
Posts: 3
Post Re: Couple of Fatman questions
Hi Bill,

Thanks for the reply. I think there are some EEPROMs that are pin-comparable with the old UV 27C64, although I do have an EPROM burner and UV eraser. I might look into EEPROMs though as it takes an eternity to flash and then erase the old parts.

Sun Apr 26, 2015 2:58 pm
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Joined: Sun Nov 09, 2008 2:49 pm
Posts: 733
Post Re: Couple of Fatman questions

Beautiful build!

It will take me some time to put together a response as to changes in the firmware as these are things that I don't recall or have not considered for at least many years... The retriggering can be canceled by going back to the last version of firmware (it would take some digging but I think I have some EPROMS with this original programming). The .lst documention available in the firmware programming download includes a section dealing with the introducing Pitch Wheel information to the VCO Pitch CV

Have you seen this PT topic about substituting an Arduino for the 8031/51? It might be something to consider, especially with all the other enhancements.

Scott Lee

Mon Apr 27, 2015 3:20 am

Joined: Sat Apr 25, 2015 6:49 am
Posts: 3
Post Re: Couple of Fatman questions
Hi Scott,

Thanks for the reply. If you would be able to find a copy of the older firmware which doesn't retrigger, that would be fantastic. I saw it mentioned in the changelog in the source but I couldn't find old compiled HEX files on the site. I understand that the new firmware fixes a velocity bug(?), but I'm not too fussed about this as I don't often use the velocity CV. As I mentioned previously, I have an old UV EPROM programmer, so this isn't a problem.


Mon Apr 27, 2015 9:15 am
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