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Some experiments with using & and USR() to call into assembly language from BASIC. Neither is very convenient when sizecoding. ; When &/ampersand call ; jumps to address $3F5 (applesoft already has a placeholder jmp there) ; when called next char/token in A (so can easily do things like &PLOT) ; can't return anything unless you look up a variable by name and ; write to the pointer ; USR() can take one argument, returns value ; jumps to $0A in zero page, which is usually a jump ; to a USER handler. BASIC is set up to illegal quant error ; by default ; need to manipulate the FAC accumulator to handle input/return https://mirrors.apple2.org.za/ftp.apple.asimov.net/documentation/magazines/misc/theappleorchard_v1n1_applesoftinternalentrypoints_ocr.pdf https://6502disassembly.com/a2-rom/Applesoft.html https://wiki.reactivemicro.com/images/f/f7/Applesoft_II_2019.pdf