instructions
a -- a a
DUP -> Duplicates byte a on the stack.
DUPw -> Duplicates word a on the stack.
DUPx -> Copies byte a on the stack to x.
DUPxw -> Copies word a on the stack to xw.
DUPy -> Copies byte a on the stack to y.
DUPyw -> Copies word a on the stack to x and y.
DUPxy -> Copies byte a on the stack to x and y.
DUPxyw -> Copies word aw on the stack to xw and yw.