> On 11 Jun 2020, at 15:14, Charles via cctalk <cctalk@classiccmp.org> wrote:
>
> =========
>
> Thanks for the tip. I didn't see in the manuals that the keyboard light
> pattern was actually a binary code, but that makes sense! I would have
> expected an error message on the screen, but as I previously noted, the video
> system itself does not seem to be working properly.
>
> Unfortunately my logic analyzer is an ancient Tek 7D01, the equivalent of
> stone tools rather than metal ;) It's not really suited for doing this kind
> of work, but it's what I have... I wonder if anyone has already disassembled
> the code?
>
> The 4116's are soldered to the board, too. Since the memory map is shown in
> the tech manual I could write a simple memory test and burn an EPROM.
>
> My fear is that one of the PALs has altered itself from tin-whisker migration
> (fuse regrowth) :(
>
You’ve just mentioned the magic 4116 word, I’d bet some of your dollars that
it’s either one of those that’s gone south or the -5V required to run them
--
Adrian Graham
Owner of Binary Dinosaurs, the UK's biggest private home computer collection?
t: @binarydinosaurs f: facebook.com/binarydinosaurs
w: www.binarydinosaurs.co.uk
