TI 990/189 debugging

Glen Slick glen.slick at gmail.com
Sat Dec 31 13:09:17 CST 2016

On Fri, Dec 30, 2016 at 6:53 PM, Josh Dersch <derschjo at gmail.com> wrote:
> Just to bring some closure to this old thread, I finally picked up a
> working TMS9980 cpu chip (after getting one faulty one off of eBay -- it
> was even more dead than the one it was replacing).  And it appears to work
> properly in the 990/189 board, with the 9.3V supplied on the CPU socket.
> Thanks,
> Josh

Now that it is working what are you going to do with it? I have
collected at least 3 of the TI-990/189 boards but have never really
gotten around to doing anything with them.

At least one has the optional serial port hardware already installed
and I have picked up a couple more TMS 9902 chips (eBay specials from
China, no guarantee they are legit and functional) to install in the
others. At some point I'll have to try getting BASIC EPROMs installed
and running on them. The cheap calculator keypads are a bit noisy and
bouncy to try to use reliably.


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