I remember playing with Dartmouth basic on 8080 assembler long ago. It was a little quirky with a limit of 32K ram. When bit 15 (8000H) was on it meant something different in the source code. Fuzzy memory about using bit 15 to signify a jump to code in the lower 32k, mask bit 15 and call or go to address. Used on goto, gosub and more spots. Microsoft borrowed heavily from Dartmouth, for MSBasic. So you could say Dartmouth Basic is the grandfather of QB64.