Below there is a list of Pins for the RS-232 port and the
corresponding pins of the RS-422 port of he Macintosh. Example: When
it says "connect this to pin number 4 of the RS-232" (25-Pin) you have to
connect it to pin 1 of the Mac port.
Pin 8 of the Mac port has to be connected to GND (Pin 4) to tell the Mac it
has to emulate a RS-232 interface, by using RXD- and TXD- (RXD+ and
TXD+ are not used). Pins 4 and 20 of the RS-232 (25-Pin) or pins
4 and 7 of the RS-232 (9-Pin) have to be connected together.
Signal 25-Pin 9-Pin Mac DSR 6 6 - DTR 20 4 1 RTS 4 7 1 CTS 5 8 2 CD 8 1 - GND 7 5 4 & 8 TXT 2 3 3 RXD 3 2 5 Front view of 25-Pin plug -------------------------------- \ 1 13 / \ 14 25 / ---------------------------- Front view of Macintosh Mini-Din-8 plug +------+ / \ / 6 7 8 \ 6: TXT+ 7: N/C 8: RXD+ | | | 3 4 5 | 3: TXT- 4: GND 5: RXD- | | \ 1 2 / 1: HSKo 2: HSKi \ / +------+