RE: Battlezone problem.

I have been doing lots of BZ work lately, please SOMEBODY come up with some
ideas on where I should go next with my problems (as per my last BZ mail).

The wd is reset by the ab9 and ab10 lines from the CPU. If those go high (I
think) it clears the WD counter.

An odd problem I am having is that my ab9 & 10 lines are working in test
mode as far as I can tell yet I still get WD bark every 3 or so seconds.
But I don't get bark in normal game mode. :(

David

> ----------
> From: jwelser@ccwf.cc.utexas.edu[SMTP:jwelser@ccwf.cc.utexas.edu]
> Reply To: vectorlist@spies.com
> Sent: Tuesday, January 13, 1998 3:27 PM
> To: vectorlist@spies.com
> Cc: jwelser@ccwf.cc.utexas.edu
> Subject: Re: Battlezone problem.
>
>
> On Tue, 13 Jan 1998, Mitchell Rohde wrote:
>
> > Now I get zilch from the unit. I didn't see squat on the data lines,
> and
> > I heard a "blip-blip-blip-blip..." from the speaker... the sound of a
> > reset. So I probed the reset circuit output, sure enough.. it's
> > going up and down about two or three times a second. If I press the
> reset
> > switch on the generator board it pins the thing in reset, but when I
> > release it goes back to the resetting...
> >
> > How does this watchdog circuit work, and has anyone seen this before?
> > What trips the watchdog?
> >
>
> Hey Mitch,
>
> Long time no "see."
>
> The watchdog is just a counter that, when it counts to its max.
> value, triggers the reset. There is an instruction (which could be just a
> store to a certian location) which clears the watchdog. So, in theory, if
> the CPU is running properly, it should clear the watchdog timer before it
> times out.
>
> If you've got schematics, there is a WDCLR signal which goes to
> the RESET line on the counter (which generates the RESET line to the CPU)
> probe it and see if it's pulsing at all. If it's not, then there is some
> other CPU problem. There is also a test point on the board labeled WDDIS
> or something like that. If you ground it with an alligator clip lead it
> disables the watchdog counter. The theory goes that if it works with the
> wotchdog disabled, then there is a watchdog problem, else there is a CPU
> problem. My Lunar Lander didn't work (i.e. stayed in RESET) despite my
> disabling the watchdog, and it turned out to be a bad watchdog counter, so
> there's no hard and fast rule....
>
> Good luck....
>
> Joe
>
>
>
>
Received on Tue Jan 13 15:50:06 1998