Changing the size of memory or changing the ROM version forces a reset of the PET.
The emulator has an IEEE-488 device at address 8. It can be used load and save (.prg) files.
Some programs don't run on ROM1 and some require more memory than the default 8K.
CHECKERS! is an implementation of the board game checkers where you play against the PET. The PETSCII board is competently drawn although the squished checkers take a bit of getting used to. Movement is simple—just enter the coordinates for the square you're moving from, and the one you are moving to—but double jumps are not automatic, so you have to tell the PET when you are making sequential captures. Be careful! I lost more than one capture because of this limitation.
The PET takes its time to decide on moves so I played through this one on warp mode. I don't know a whole lot about checkers aside from the rules, but from my beginner's vantage point, it seemed that the computer was a cautious player. It responded to my obvious threats and even managed to gain the upper hand at one point. I think it is able to deal with short-term tactics but is hopeless with long-term strategy.