1: .globl backspace 2: .globl lookchar 3: .globl w, r, a, l 4: / 5: / routine to read a string backwards 6: / the read pointer is decremented before reading 7: / 8: / mov ...,r1 9: / jsr pc,backspace 10: / mov r0,... 11: / 12: backspace: 13: cmp a(r1),r(r1) 14: bhis nochc 15: dec r(r1) 16: jsr pc,lookchar 17: rts pc 18: nochc: clr r0 19: sec 20: rts pc