Retro Challenge 2015 – Update #2 – Serial Comm Established

Thanks to an awesome blog post over at Biosrhythm, I now have RS232 serial communication to/from the Commodore 64.  I built what is essentially the exact same adapter that he used.  The only minor difference is mine is based on the MAX3232 chip.

So I wrote some code based around some code samples I found online.

Then I ran some serial communication tests to and from a PC, first inbound:

Then outbound (which will become important when sending data to the printer):

Worked like a champ, here’s a shot of the User Port to RS232 adapter:

I’ve also run the self-test on the receipt printer (which finally arrived at my doorstep today):

I also ran some serial communication to the printer via serial from my PC.  Just testing, and it seemed to work perfectly.

I’m “this close” to having this work, unfortunately I don’t have any Male DB9 connectors floating around and can’t find my stash of serial gender changers.  I’ll pick some up after work tomorrow and I should be up and running at that point.  Updates to follow.  🙂

One Response to “Retro Challenge 2015 – Update #2 – Serial Comm Established” »»

  1. Comment by Paul | 01/17/16 at 8:47 pm

    Great project! Glad the DIY RS-232 adapter idea on my site ( helped you.

    I’ve always wanted to experiment with one of these receipt printers so I’m very happy to see that you’re doing just that.

    Just an FYI, the RS-232 serial routines on the C64 are borked and usually have problems running at anything above 300 baud reliably. The UART is in software rather than a hardware UART. The thing that might help you out here is that the C64 would be sending only (right?) to the printer and doesn’t need to receive. In any case, just wanted you to be aware in case you run into problems down the road.

    Good luck!

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