[Newer Macs serial connection]

Apple Macintosh 128/512K serial connection

The printer and modem ports on Mac 128/512K machines from the mid '80s used this pin-out:
Pin    Signal   Direction         Remarks
---    ------   -----------       --------
 1     Gnd
 2     +5 V     Voltage from Mac
 3     Gnd
 4     TxD+     Voltage from Mac  leave open for RS-232
 5     TxD-     Voltage from Mac  use this pin when connecting to RS-232
 6     +12 V    Voltage from Mac  HSKo, Handshake output DTR
 7     HSKi     Input to Mac
 8     RxD+     Input to Mac      connect to ground for RS-232
 9     RxD-     Input to Mac      use this pin when connecting to RS-232
The jack on the chassis of the Mac is a female socket.

A cable to connect an old Mac 128/512K to serial printers such as the HP DeskWriter or Apple Imagewriter II is available from MacWarehouse (800-255-6227). It has a DB-9 male plug on one end and a DIN-8 plug on the other. (Item number ACC 1312, $4.95 plus $3 for overnight shipping.) The DB-9 end is not wired to transfer data to a PC. This cable is also sold by www.pacificcable.com

Made with MacintoshPlease send your comments and suggestions.
John Neuhaus, WA2JXE
john at jneuhaus.com

Last revised: Sat, Jul 28, 2001