The RS-232 standard on the C64 is a little bit strange. It uses inverted TTL level for the signals. The RS-422 ports on the Macintosh has both an inverted and non-inverted input. By using the inverted instead of non-inverted the inverted C64 level is back to normal.
(at the Computer)
(to the C64).
8 PIN MINI-DIN MALE to the Macintosh.
DZM 12 DREH to the C64 UserPort.
Contributor: Joakim Ögren, Pierre Olivier
Usenet posting in comp.sys.cbm, A very simple C64 to Macintosh serial cable by Chris Baird
Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-08