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.
The PET gives you a length, and you have to draw a line that stops at the correct fractional marker on the ruler. This is a simple drill program, beautifully executed.