instructions a -- a-- DEC -> Decrements the top byte on the stack by 1 DECw -> Decrements the top word on the stack by 1 DECx -> Decrements x by 1 DECxw -> Decrements xw by 1 DECy -> Decrements y by 1 DECyw -> Decrements yw by 1 DECxy -> Decrements x and y by 1 DECxyw -> Decrements xw and yw by 1