Sometime in the 2000s, I think, when the Computer History Museum was restoring its PDP-1, they stumbled on some tapes or something that held inputs - entire classical works like Mozart's Eine Kleine Nachtmusik - for Peter's synthesizer. Unfortunately they couldn't locate a copy of the synthesizer program itself but, being one of the OG hackers, Peter was able to examine the data on the tapes, reverse-engineer the data format he'd invented decades prior, and write a brand new synthesizer for the PDP-1 that was compatible with the original tapes. All of those adages about data structures being more important than code suddenly rang true in a very real way :-)
He told the story over a live demonstration of the PDP-1 playing music with his program - it's a wonderful experience and if you have the chance to see it, you shouldn't pass it up [2]. If you have a chance to see him at the Computer History Museum, don't pass it up! Steve Russell joins him with a Spacewar! demonstration (you get to play it!) and they're happy to answer questions and recount stories about their old days in the MIT Tech Model Railroad Club :-)
[1]: http://en.wikipedia.org/wiki/Harmony_Compiler
[2]: They have the PDP-1 demo on two days of every month, twice a day. http://www.computerhistory.org/hours/