Nice! I like that controlling it is a simple matter of "MOTOR ON" and "MOTOR OFF".
I found the article you're talking about here: https://archive.org/details/P100-Magazine/1989-01/page/5/mode/1up (The key detail is that the pins the MOTOR command connects are 1 and 3 on the cassette port. Don't switch more than 12V, 200mA.) Controlling 8 relays from the printer port I can understand — each bit of the output byte maps to one pin — but how did you do 16? And what does the interface from BASIC look like? --b9 On October 18, 2025 6:11:50 AM PDT, Scott McDonnell <[email protected]> wrote: >I am sure most people were already aware of this, but thought I would mention >it for those that didn't: > >The cassette port has a single relay used to control the remote input on a >tape recorder. This is a fairly low current relay. It controls the voltage to >the motor in a tape player/recorder acting much like a pause button. > >Since it is fairly low current, you probably wouldn't want to use it directly, >but what can be done is to use it to drive another larger relay. It is >perfectly capable of driving the coil of another relay. > >This gives you a simple real-world interface already built in. > >The circuit is really simple for those handy with electronics. But for those >that need more information, there is actually an article in the January 1989 >issue of Portable 100 (page 6) which gives the details and programming >information. > >I am soon putting together a simple example of controlling 8 and 16 relays >from the printer port. Nothing fancy, but if there is interest in the details >for it, let me know. > >Other mods I have been talking about are waiting for a few more parts >(shipping has been VERY slow lately) so that I can get in there and just do it >all at once. >
