Philippe Riviere's Macintosh modifications for the Twiddler, as taken, require disassembly of the Twiddler to get access to the Berg 5 pin connector. Fortunately, it is possible to gain access to the required pins through the Twiddler's external connectors, to build a "Mac adapter cable" for the Twiddler. This cable can then be disconnected from the Twiddler to allow it to be connected to a PC.
Two of the wires on the Twiddler's end are available from either of the DIN-5 connectors; the other two can be obtained from the DB-9 connector. The original schematics can then be followed to construct the adapter cable.
The overall parts list looks like this:
Cut off the PS-2 side of the keyboard adapter and strip back 3/4" of the outer insulator. Five wires will be visible inside, corresponding to the colors listed in Mr. Riviere's documentation. The orange and yellow wires are connected, and can be spliced into the middle of the ADB cable to provide power to the Twiddler. Note that there are several connections that ultimately must be made to the orange wire. The brown, red, and black wires from the PS-2 adapter are not connected and may be cut off.
The "red" and "brown" wires listed in the Mac schematics correspond to pins 2 and 4 of the DB-9 connector; use the male DB-9 connector above to mate with the Twiddler's and thereby obtain these connections. The schematics can be followed from here with respect to connecting the four wires from the Twiddler to the Mac ADB and serial cables.
This cable worked on a Power Macintosh 7100, a Quadra 950, a Macintosh IIfx, and a Centris 650. We had varying degrees of success using the computer's keyboard and mouse at the same time as the Twiddler; on the Power Mac these devices did not work at the same time the Twiddler was active. The cable did not work on a Powerbook Duo 270c, even with the full MiniDock attached.
Kenneth B. Russell (firstname.lastname@example.org)