.define Exg2 ! This subroutine exchanges two words on top of the stack. ! The top word of the stack is really in the AX registerpair. ! So this word is exchanged with the top of the real stack. Exg2: pha ! save A txa pha ! save X jsr Pop ! get top real stack stx EXG sta EXG+1 ! save top of real stack pla ! get X tax pla ! get A jsr Push ! push on real stack ldx EXG ! get new X lda EXG+1 ! get new A rts