Re: Major Havoc help (was: Vectrex on Vector Monitor?)

Clay,

I've been keeping this e-mail around as debugging tips, but I realized that I
have NO IDEA on how to actually do the things you mention. See my
question/comments below...

On Aug 12, 10:56am, Clay Cowgill wrote:
> Subject: RE: Major Havoc help (was: Vectrex on Vector Monitor?)
> > >quit reading it after arguing with some twit for far too long about
> > 6809
> >
> > "twit" huh? Not very nice :)
> >
> :-) *grin* I probably should've put a smiley in there, but I was
> typing fast before a meeting... ;-)
>
> > Speaking of twits, I have a couple MH boards I would like to resurrect
> > from the grave. Board repair is not my specialty, but I have the
> > capabilities to do it. Anybody have some tips/Atari signature guide/
> > anything to help me with this task?
> >
> What kind of problems are they exhibiting? I've had good luck fixing
> vector boards just starting at the crystal and tracing through the game
> with nothing fancier than a logic probe. (A LOT of vector boards are
> "resurrected" just by replacing a dead crystal, IMHO.) Just step
> through it logically:
>
> Is the clock running? (check crystal and clock on microprocessors)

Which pin is the clock on microprocessor, assuming Z-80? assuming 6809?

> Is the board coming out of reset? (check watchdog outputs and reset
> pins)

Which pins are reset pins?

> Does it look like the processor is running? (check datalines and address
> bus for activity)

Which are data lines?

> Is it doing something useful? (see if chip selects on multiple ROMs are
> occuring)

What/where is chip select?

> Is the Vector generator running? (check the signals in the vector
> generator-- "GO, Reset, etc." is it hitting the Vector generator ROM?
> Is the vector generator ASIC good?)

Huh?

> Are the DACs getting input data?
> Are the DACs generating output voltages that make sense?
>
> I find the majority of problems in the clock circuit, followed by the
> vector generator (usually after the DAC outputs), and then the program
> ROMs....

I think this is all good advice in general, but us dummies who don't have
volumes of computer chip books (I don't even have ONE) could use some herding
in the right direction...

Thanks! (PS. When do Multi-pac's start shipping again? I haven't received
mine yet...).

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Mark Jenison E-mail address: jenison@cig.mot.com
Cellular Infrastructure Group Motorola--Arlington Heights, IL
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Received on Thu Oct 29 16:18:37 1998