DECLARE SUB sti ()
DECLARE SUB cli ()
sr% = 1
cli
DO
 s% = s% + sr%
 IF s% > 200 THEN sr% = -sr%
 IF s% < 0 THEN sr% = -sr%
 WAIT &H3DA, 8, 8
 WAIT &H3DA, 8
 OUT &H3C8, 0
 FOR i% = 1 TO s%
 WAIT &H3DA, 1, 1
 WAIT &H3DA, 1
 NEXT i%
 FOR i% = 0 TO 63
  WAIT &H3DA, 1, 1
  WAIT &H3DA, 1
  OUT &H3C8, 0
  OUT &H3C9, 0
  OUT &H3C9, i%
  OUT &H3C9, i%
 NEXT i%
 FOR i% = 63 TO 0 STEP -1
  WAIT &H3DA, 1, 1
  WAIT &H3DA, 1
  OUT &H3C8, 0
  OUT &H3C9, 0
  OUT &H3C9, i%
  OUT &H3C9, i%
 NEXT i%
 OUT &H3C8, 0
 OUT &H3C9, 0
 OUT &H3C9, 0
 OUT &H3C9, 0
LOOP UNTIL INP(&H60) = 1
sti

SUB cli
 a% = &HCBFA
 CALL absolute(VARPTR(a%))
END SUB

SUB sti
 a% = &HCBFB
 CALL absolute(VARPTR(a%))
END SUB