Vintage Synth Repair

There's an eBay seller (based in California I think) that has two different 8021 replacements specifically for the Pro-One. One replaces the original functions and the other adds MIDI capability as well as the original functions.  Also, if I remember correctly, these replacements expand the number of sequencer steps available by quite a bit.  There are none currently listed but they pop up every few weeks.  They're little PCB assemblies using modern components that plug into the original 8021 socket.  The MIDI version also comes with a midi interface PCB assembly and requires some modification to the Pro-One housing to accommodate the MIDI connector and to mount the interface PCB.  Working from memory, I think the costs are about US $129 and $189 respectively but don't quote me.  I've been thinking about getting the MIDI version as I have a Pro-One main board without keyboard or housing but populated with all of the custom VCO-VCF-VCA chips but Ive
 had other priorities.  I have a saved eBay search that these guys show up in every now and then so I'll post the link the next time this guy lists either one.
 
There may be an problem if you get an original 8021. I have been told (but have not confirmed) that you need the program mask in order to instruct the 8021 what to do in order to make it work with the Pro-One.  Without that, it's just a black rectangle with silver legs.  I read someplace, years ago, that this same IC was used in a number of original Apple MacIntosh keyboards. 
 
Perhaps someone with more knowledge can either confirm or refute my program mask statement.
 
            James



From: Nicolas <nico678@...>
To: vintagesynthrepair@yahoogroups.com 
Sent: Thursday, August 15, 2013 10:31 AM
Subject: [vintagesynthrepair] Sequential Circuit Pro One UPD8021 chip

  
Hi everybody,

I'm looking for a UPD8021 microcontroller chip for a Sequential Circuit Pro One synthesizer. 
Does anybody knows a source or a replacement for this chip?
Thank you!

Nicolas