Re: [stella] Cool new toy!

Subject: Re: [stella] Cool new toy!
From: Chris Wilkson <cwilkson@xxxxxxxxxxxxx>
Date: Sat, 14 Mar 1998 22:56:16 -0800 (PST)
> > I just found another function on my o'scope.  Video mode.  Yep, I can feed
> > a video signal directly into my scope and set it to trigger on any scanline.
> > I'm not sure, but I think it should work on NTSC or PAL signals.  Could be
> > useful for tracking down occasional glitches/cycle counting issues.
> The most useful debugging tool mentioned by the classic programmers was
> the HP logic analyzers.  These provided all sorts of frills.  It's kinda
> over my head so I'd have a hard time explaining what they do, but anybody
> who is really hard-core in their programming could probably get a lot out
> of use out of these things.  I believe they clipped onto the 6502 and they
> could actually disassemble code on the fly and monitor all the signals
> coming off the pins.

Yep, I have one of those too!  <evil power-mad grin>

Problem is, I don't have the manuals, etc, so I'm just sorta trudging along.
Thus the lag time in the video sync discovery...I've had the scope for almost
3 years!!!  Guess this is the price I pay for buying used equipment at swap
meets.  :)

The logic analyzer can take an external trigger.  So the idea goes something
like this...You feed the analog video signal to the scope to generate a 
trigger pulse.  Send this to the logic analyzer, and you can capture up to
1K states for as many as 80 syncronous signals.  And my particular analyzer
can let you assign symbols to particular values, so I will actually see
"STA WSYNC" on the screen.'s a nice analyzer.  :)
This is kinda time comsuming the first time around.  Not to mention running
those 80 probes to the board.  And if a probe comes lose, finding the exact
culprit is torture.

The analyzer setup is a bitch, but once you get it working, it's sweet!!

Although I haven't had a chance to really put this to work, I agree with the
classic programmers.  The potential is staggering.  I've been thinking about
designing some daughter boards to interface between the three chips and the
2600 mother board.  I could run all the relevant signals to IDE-type headers,
and just plug the analyzer into that.  This would simplify the setup immensely.

Personally, I'm years away from needing this for software debug, but it will
be useful for debugging all the peripherals that I'm designing.  :)


Archives (includes files) at
Unsub & more at
Don't post pirate BINs to Stellalist.  Be a programmer, not a pirate.
Write the best game, win framed autographs of famous Atari alumni!!

Current Thread