#mac plus

Fun old tech on display at the Fall 2025 Dallas/Fort Worth area Retrocomputing Meetup on the 18th of October, 2025.

Tonight I watched a video on YouTube that attempted to clear up the mystery of how this scene was accomplished in Star Trek IV The Voyage home..

What I thought it was was (probably) totally incorrect I've found out.

Apparently, the Mac Plus was a modified one with a 24FPS CRT TV replacing the macs monitor and it was being fed footage from a video tape system that was made on an IBM PC rather than any Apple hardware.

They designed it to mimic what Mac OS (then called "System #" instead of Mac OS #) looked like but it kinda threw me off because to it resembles the GUI OS on Apple // machines to me more than Mac OS especially because it didn't have the black border around the desktop and it as significantly lower resolution. Unlike this example:

I just always thought they hooked up an Apple // offscreen and used GS/OS there.. Such as this example which IMHO looks a lot more like the screen in Star Trek 4 apart from the color.

Last year I revived an old Mac Plus that had been destructively robbed for parts over the years. I added sockets for the chips that had been removed, gave it a new power supply, added my SE-VGA card for video, and bodged a few broken traces. But there still remained the most heinously destructive part removal that had been committed against this poor board ...

Long before I had mastery of a soldering iron, and lacking the proper tools for desoldering components successfully, I had a project where I needed n 8-pin mini DIN connector. I had this non-functional Mac Plus board gathering dust so I decided to remove one of its connectors. With a knife. By cutting the board around the connector.

I was young ...

Obviously, there's no repairing that. The board has a permanent chunk removed from it.

However, I find myself wanting to be able to use those serial ports now that I have the rest of the board running. There are lots of fun things to use them for, like LocalTalk networking, printers, zTerm, etc.

So I set out to build a breakout board to add the connectors for these serial ports back to the board. I started by digging up datasheets for the RS-422 & RS-232 transceivers Apple used, as well as schematics for the Plus and similar era Macs so I could trace out how the connectors were originally wired. It turns out all of the signals for both ports are routed to some RC filters in a straight line at the back of the board. This made it fairly easy to solder a ribbon cable to the filter pins on the back side of the board.

I've come to like ribbon cables; they're easy to work with. I can just crimp an IDC connector on one end and attach them to some pin headers. The breakout board itself is just some generic protoboard, and has said pin headers and two female 8-pin mini-DIN connectors.

It's not ideal. The ribbon cable wires are fragile and cold easily be pulled off the motherboard. But hopefully this will restore the last lost functionally for this poor tortured Mac Plus motherboard.