2023-07-05 — updated 2023-10-04
The Macintosh SE/30 has great expansion possibilities with logical support for up to 6 PDS cards using 120-pin, 3-row DIN 41612 sockets. However, it’s hobbled by a single slot and case size limitations. A number of cards support a passthrough slot to resolve this limitation, and in some cases this can be used to install 2 cards simultaneously.
However, we’re still left with two limitations:
- The vast majority of cards with a passthrough slot are designed for a IIsi which has different case dimensions.
- It’s often desirable to fit 3 cards (more than 3 really starts to become an impossiblity unless you remove the case.
You can find a nice index of potential configurations on the High Intellect wiki.
However, many of these configurations require a right angle direction change adapter, which has traditionally been difficult if not impossible to find. There’s good news, however:
- As of this update (July 2023), there are still supplies of right angle sockets.
- Right angle sockets can reliably function as right angle adapters by “plugging” the solder pins into the base socket.
It’s worth defining the difference between a direction change adapter and a socket. An adapter normally has male pins on one end and a female socket on the other. A plain socket has solder pins intended to solder to a circuit board on one end and a female socket on the other. Conveniently, DIN 41612 connectors typically use the same pin pitch on the circuit board and connector itself, meaning the solder pins are actually compatible with normal male pins to a degree and they can be plugged together.
Thus, we can substitute a 120-pin, 3-row DIN 41612 right angle socket. TE Connectivity still manufactures part 5650874-5, and 3M makes part DIN-120RSC-SR1-KR. You can find these at typical suppliers like Mouser and Digikey.
I’ve personally had success with the TE 5650874-5 in my SE/30, but the 3M part should work as well.
To use, plug the pins into the passthrough socket in the correct orientation on the first card, then plug the second card into the right angle socket. Not all boards will fit in this configuration, so it’s worth checking clearances. Additionally, this setup is quite delicate, so use care when inserting or removing cards. Finally, when (ab)using a socket there is no enforcement of directional keying. As a result, it is possible to plug in the second board upside down, which will likely permanently damage one or both cards and your SE/30. Thus, it’s always recommended to check for expected voltages and signals on the socket before mounting the second card.