Earlier this week we mentioned that Apple was donating the source code for its MacPaint software to the Computer History Museum in Mountain View, Calif. Since the story first published, Andy Hertzfeld, the man responsible for the donation, offered a few new details. Hertzfeld, a member of the original Macintosh team, wrote BusinessWeek to clarify a couple of questions from readers, including the format of the disks.

“We used the Lisa to develop the Macintosh system software and original applications because it had a hard disk and enough RAM to run development tools like the Pascal compiler, which the Mac did not,” said Hertzfeld. “The development system we used was called the ‘Lisa Monitor,’ which was a port of the UCSD Pascal system done for the Lisa by Rich Page in 1979, so the disks were in the Lisa Monitor format.”

Hertzfeld also said he used a 1996 Mac to extract the original files and then transferred them to a modern machine using Ethernet.