I want to make a test unit some day: - Test Math results / Binary Coded Decimal - Test 0xF Flag on AND, OR, XOR, ADD, SUB, Collision - Test syscalls - Test Save/Load RPL flags - Test Call / Jump - Test for Vertical Wrap hack (Blitz was created on machines that didn't support vertical wrap) - Test for normal wrapping - Test fonts - Super Chip8 tests - maybe mega chip tests? Note about hybrid games: They are special chip8 programs containing native runtime code. Some are really whole native programs that doesn't use the chip8 interpreter at all (I wouldn't call them chip8 programs or hybrid ). The normal [real] hybrids just use syscalls to call native CDP1802 code inside the rom itself which help chip8 games access any part of memory such as the video buffer, chip8 registers, stack memory, chip8 interpreter work memory. Also can read the cdp1802 register for some info such as pointers, PCs, and interrupt info. I also think its illegal in chip8 programming to have programs call code outside the rom such as interpreter code or the HW rom.