On Sat, Jun 13, 2020 at 11:00 AM David Gesswein via vcf-midatlantic < vcf-midatlantic@lists.vcfed.org> wrote:

Not an 8080 guy so somewhat generic suggestions.

...

Ive done the kill-the-bit game and played music to an AM radio.

I assume these jump. Can you tell any difference in what jump used or where your running from in memory?

I assume 8080 restarts with interrupts disabled so the serial port can't be triggering an unhandled interrupt.

What port is the echo test program expecting to use? Is it the echo program from solivant.com. That one is port specific. Altairs don't always match non MITS cards by default. If you're using an echo test program be sure you have the correct port (octal 0 , 10, 20, etc.) . I'd try using a known working serial card if you have one, first. You can bring your altair to kennett classic if you want. I have four altairs here set up at the moment. Please contact me privately if you plan to come up, safety rules for COVID, etc. Bill