Quicktake Apple IIc cable

The problem:

The ACIA 6551 can not communicate with DTR down. Turning DTR off
effectively shutdowns the ACIA.
The Quicktake 100 wakes up and starts communicating only when DTR
goes from up to down. If DTR goes back up, it stops communicating.
Hence, there is no way to wake up a Quicktake 100 with an Apple //c
serial port.

The solution:

The Apple //c has two serial ports. We will transfer data from the
Quicktake 100 digital camera using the modem port, and wake it up
using the printer port. Our cable will have one Mini-DIN-8 connector
on one end, a DIN-5 connector on the other end, and... a DIN-5
connector on the third end.

The cable wiring scheme is the following:

Mini-DIN8       Modem DIN5             Printer DIN5
1 -             -                      -
2 (DTR)         -                      1 (DTR)
3 (RX)          4 (RX)                 -
4 (GND)         3 (GND)                -
5 (TX)          2 (TX)                 -
6 -             -                      -
7 (DTR)         -                      1 (DTR)
8 -             -                      -
                1-5 (DTR-DSR shorted)

Mini-DIN8 pins 1, 6 and 8 are not connected to anything.

Mini-DIN8 pins 2 and 7 are connected together to one of the DIN5 pin 1.
This DIN5 connector will be plugged in the printer port.

Mini-DIN8 pins 3,4,5 are connected to the other DIN5 pins 4,3,2.
This DIN5 connector will be plugged in the modem port.

Mini-DIN8 pins numbering, as seen when looking at the front of the connector:

  6 7 8
 3 4   5
   1 2
   
DIN5 pins numbering, as seen when looking at the front of the connector:

 1       5
  2     4
     3
