Simple Commodore PET Tape Interface
September 5, 2017 2:40 am ProjectsBefore I put together a long term solution, I wanted a quick way to transfer software from my PC to my Commodore PET. There are other circuits, but I wanted something that used just one part.
The PET input is TTL level, so I needed something to go from audio level to TTL. Ideally a comparator circuit with plenty of gain. Well, I couldn’t find a decent comparator in my junk box, but I did find a CA3140 op-amp. This is way faster than I needed, but should work OK as a comparator. If you build this circuit, try to find a comparator or an op-amp with a rail-to-rail output.
Here is the circuit:
And here’s what it looks like:
It works quite well. The circuit is not very sensitive to the output audio level from the PC–I set mine halfway (line level) and it was fine.
Vintage Volts :
Date: March 11, 2019 @ 11:59 am
I like the one chip simplicity. I’m guessing it’s “read only” though, which is fine due to mainly wanting to run stuff on the PET these days as opposed to typing in programs on the PET like the old days and saving copies of them.
So far, my PCPET solution is a Bluetooth cassette I use for my motorcycle radio, that also happens works in my C2N cassette drive. It also suffers from having to get the PC volume just right, but it works. It’s also one way for loading BASIC programs from the PC to the PET. Then I just stick in a regular cassette and save it back to tape.