Is there even an environment you can program in? Can Applescript on classic macos do serial stuff in any form?
/? farallon Mac serial port Ethernet https://www.google.com/search?q=farallon+mac+serial+port+eth... : $50 and no FreePPP or Zmodem or AppleScript serial port to a [soldered] cable to an Arduino/RP2040W/ESP32 (which is probably faster than the old Mac).
https://unix.stackexchange.com/a/548343/44804 mentions minicom and gnu screen, and the need to implement e.g. file-level checksums because over serial like ROM flashing
Even if you didn't have one of the dozens of already written serial terminal apps, you could write your own pretty easily in one of those languages to push bytes out the serial port, with just a few standard API calls.
I doubt MacOS didn't have something similar. Unless of course, MacOS back then was somehow shittier than Windows, which I doubt.
[1] https://learn.microsoft.com/en-us/dotnet/api/microsoft.visua...
It might not. A lab I was at in uni still had Windows XP PCs because according to them, that's the last Windows OS that allowed direct serial/paralel port access needed to control the external robotics/CNCs via those old APIs the SW used, since subsequent versions of Windows abstracted away those direct HW API calls that DOS used in the name of security and stability.
Not the greatest tools out of the box, but still better than nothing.
ref: https://en.wikipedia.org/wiki/.NET_Framework_version_history...
