Connecting your Lucid programmer to a Mac's serial port

The "standard" Macintosh serial port is an 8-pin mini-DIN. If you look at the back of a Macintosh you should see a connector like the one shown here. This picture shows the female side. The cable connector (the male side) would be a mirror-image of this.
shieldGndFrame ground
1HSKoOutput handshake
2HSKi/ClockInput handshake or external clock
3TxD-Transmit data (minus)
4SGSignal ground
5RxD-Receive data (minus)
6TxD+Transmit data (plus)
7GPiGeneral purpose input (not on Mac+ or earlier)
8RxD+Receive data (plus)

You'll notice these signals don't have the usual RS-232 names. This is because the Mac uses RS-422, where each signal is sent over a balanced pairs of wires, a positive (+) and a negative (-). In RS-232, the data signals are inverted; a one, marking, is minus voltage. However RS-232 control signals are not inverted. Since the TxD- signal from the Mac is inverted it can be used to drive an RS-232 receiver. Leave the TxD+ signal disconnected. Similarly, the receive data signal from RS-232 equipment is inverted, so it can drive the Mac's RxD-, but in this case the RxD+ line is grounded since the RS-422 receiver in the Mac needs valid levels on both inputs. The following page provide more in depth discussion of Macintosh serial interfacing - Macintosh Serial Port Connections, University of Utah.

The table below shows cable wiring to connect a Lucid Technologies programmer to the Mac's serial modem port. Since I don't have a Mac, any corrections or updates would be appreciated.

Mac DIN8 to Lucid DB9 programmer cable, no hardware handshake

 Mac DIN8     Lucid DB9 
 4 (SG)       5 (SG)
 8 (RxD+)     5 (SG)
 5 (RxD-)     2 (RD)
 3 (TxD-)     3 (TD)
On the DIN8 end of the cable, connect pin-1 (HSKo) to pin-2 (HSKi). Unspecified pins on both connectors are allowed to float.

Macs with DB9 serial connectors

Apparently the Macintosh 128K, 512K, and 512K Enhanced use a DB-9 connector for the serial ports. The pinouts for the DB-9 connector is shown below.
Pin    Name       Function     
 1     SG         Signal ground
 2     +5V
 3     SG         Signal ground
 4     TxD+       Transmit data (plus)
 5     TxD-       Transmit data (minus)
 6     +12V
 7     CTS        Clear to send
 8     RxD+       Receive data (plus)
 9     RxD-       Receive data (minus)

Mac DB9 to Lucid DB9 programmer cable, no hardware handshake

 Mac DB9      Lucid DB9 
 3 (SG)       5 (SG)
 8 (RxD+)     5 (SG)
 9 (RxD-)     2 (RD)
 5 (TxD-)     3 (TD)
Unspecified pins on both connectors are allowed to float.
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