Writing to the bank select register at $EFFC selects bank 0-15. The expansion RAM is divided into 16 banks of 4K each. It contains 32K from $0000-7FFF, as a CBM 8032 does, and an additional 64K of expansion RAM. OperationĪ stock SuperPET has a total of 96K RAM. You can also try Super-OS/9 using the VICE emualtor (see below). If you would like to build your own, Jim Brain now sells a PCB and parts kit. I then reverse engineered the board from the photos and built my own working replica using point-to-point soldering.
In 2009, I received the Super-OS/9 boot disk and photographs of the original MMU printed circuit board from TPUG members Golan Klinger and Steve Gray. The daughterboard allows a 6809-mode program to select between the normal memory map and one of 64K contiguous RAM ($0000-FFFF) to provide more useful working memory to OS-9.
In 1985, Avygdor Moise and other members of the Toronto PET Users Group (TPUG) ported Microware’s OS-9 Level I operating system to the Commodore SuperPET.Īs part of this port, they created a small Memory Management Unit (MMU) daughterboard.
