Oh, interesting. GeoPort. Connect to phone lines without a modem, a great feature on early Macintosh computers that outperformed PC softmodems.
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Important! Again, I reiterate, because this is important! Wikipedia said that the serial ports on the Macintosh can actually be put into either RS-232 or RS-422 mode. You don’t need the special cable convert to go from RS-422 to RS-232.
- CLARIFICATION: This came from the Wikipedia article and is actually misinformation. The only conversion that happens is that through the use of specialized cables. See the following information sources for more information.
20180323/DuckDuckGo macintosh run serial ports in rs-232 mode
This page provides very comprehensive information on interfacing Macintosh serial ports with commodity PC hardware, including wiring a LaserWriter to a PC serial port.
20180323/https://terpconnect.umd.edu/~zben/mac/MacSerHard.html
20180323/DuckDuckGo macintosh rs-232 serial cable
20180323/https://en.wikipedia.org/wiki/RS422
20180323/DuckDuckGo macintosh rs-232 serial cable mini din
Some online cables that I could buy? Given the previous sources, better double-check them manually before plugging them in. Oh, fine, the old fashioned computer usage style.
20180323/https://www.cablestogo.com/product/25041/6ft-db9-female-to-8-pin-mini-din-serial-rs232-male-adapter-cable
20180323/https://www.cablestogo.com/category/pc/pc-serial/8pin-minidin-serial-cables
20180323/DuckDuckGo macintosh rs-422 rs-232 modes
20180323/DuckDuckGo macintosh connect to rs-232 modem
Lesson learned: DO NOT follow incorrect information on the Internet! It is RS-422, and it needs to be converted to RS-232.
20180323/https://www.dr-lex.be/random/pcmodemmaccable.html
20180323/DuckDuckGo macintosh difference between printer and modem serial port modes
This is a very interesting page with lots of information on the history of Apple computer connectors. Not entirely correct on the serial port part, though.
20180323/http://lawlor.cs.uaf.edu/~olawlor/ref/mac_ports/index.html
20180323/https://en.wikipedia.org/wiki/PhoneNet