Found the old email, that problem I was thinking about was on an Apple 2, so this probably is different. Can I assume that these random characters end up in the input buffer and mess up the syntax of whatever you were trying to type?
The flickering power light on the keyboard is probably a major clue. That is powered by the +5volts supply to the keyboard and should be solid on. First thing I would do is check out +5 volt connections between keyboard and motherboard.
Second thing I would do is get it back into the state where spurious input is occurring and disconnect the keyboard and see if it continues without a keyboard attached. If the problem stops happening, it is pretty likely that it is the keyboard or keyboard connections.
Older Apple II keyboards are well known for all kinds of key switch issues, including keys that repeat randomly.
--- In email@example.com, "Mike" <mike@...> wrote:
> This problem with spurious characters rings a bell - now to remember what it was. I do think it had an easy solution. I might have to dig through my email archives.
> Mike W.
> --- In firstname.lastname@example.org, "Evan Koblentz" <evan@> wrote:
> > >> Can you describe any triggers
> > I can describe the symptoms. We were using the computer all day, on both days, and it tended to spit out random characters when just sitting there with BASIC loaded. We also noticed the power light flickering on the keyboard (Corey used an Apple II keyboard, as you know.) The problem started happening after several hours of use on Saturday; we never saw it before that. Corey noticed it first and suggested that it could be the venue power. I thought, we should've brought a UPS. Luckily the issue had minimal impact on our demo.
> > Also, I managed to crack a glue seam on the enclosure sometime between moving the computer from InfoAge and arriving at Maker Faire. The back and sides are separate parts. Corey said he will take that as an opportunity to build an even nicer enclosure out of single piece.
> > I'm excited about that because it also means the new enclosure will have its edges smoothed down, etc., unlike the current one which passes the 10-foot test but isn't as polished up close. We all saw how professional his second design looked (at VCF East); number 2 (assuming we start with 0) should be the best one yet.