10REM Save memory on ^Z
   20REM restored on BREAK.
   30REM Use as an alternative to *AUTO, for explicit backups/checkpointing
   40 
   50InsertV = &22A
   60Code=&A00
   70FOR Pass=0 TO 2 STEP 2
   80P%=Code
   90[OPT Pass
  100.install
  110  PHP:SEI
  120  Lda InsertV:Sta olde
  130  Lda InsertV+1:Sta olde+1
  140  Lda #evrt MOD 256:Sta InsertV
  150  Lda #evrt DIV 256:Sta InsertV+1
  160  PLP
  170  Rts
  180.evcode NOP
  190.olde NOP:NOP
  200.evrt
  210  PHP:PHA:TXA:PHA:TYA:PHA
  220  Cpx #0 \ Keyboard ?
  230  Bne ignore
  240  Cpy #ASC("Z") AND 31
  250  Bne ignore
  260  Lda #143:Ldx #49:Jsr &FFF4
  270  CPY #0:BEQ RESUMED
  280  PLA:TAY:PLA:TAX:PLA:PLP
  290LDX #&FF:TXS
  300Lda #&81:STA &FE4E
  310CLI
  320BRK:EQUB &FF:EQUS "Suspended (BREAK to resume)":EQUB 0
  330.RESUMED
  340  PLA:TAY:PLA:TAX:PLA:PLP
  350  RTS
  360.ignore
  370  PLA:TAY:PLA:TAX:PLA:PLP
  380.his
  390  Jmp (olde)
  400]
  410NEXT Pass
  420*SAVE $.CtrlZ A00 B00 FFFF0A00 FFFF0A00