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You should run the vector generator tests after verifying that the ram is ok. Start with the halt test and move on from there. You can check the halt times to see if at least the digital part of the vector generator is working. If the vector generator is getting stuck then the game will be...

You can use the tester to check the vector generator without the math box connected. That would be a good place to start. The game should also display test mode with the math box disconnected.

I'm not sure why ram chips would prevent the FPGA tester from connecting - I have not seen that before. In terms of the vector generator, you want to start with just the "halt" test and go from there. If you can't get that to work (or the timing is off), you want to focus on getting that...

Good luck tracking things down. I usually ground the clock and start connections (currently using the twisted pair wires) but the data probe can often be used without connecting ground which makes it easier to move around. Bad count could be either the clock or the start/stop signal. You...

If C8 pin 1 is failing it would be good to see where it is failing by looking through the trace (where does it turn red?). Is the entire trace failed or does it start OK then fail? The "timer" signals that drive these inputs (through the LS08 and gates) to the state prom are actually the...

Keysight DSOX1102 Acquisition Menu - Time mode XY, Acq Mode HiRes (the hires mode is important here - it must average samples to get higher resolution) Display menu - Persistence Variable - Time 200ms - you can play with this to get more "trailing" stuff on the vectors if you want. Adjust the...

Here's a video of the Keysight scope running the battlezone attract screen and test with the blanker board mentioned earlier..

Just saw this thread pop up again and I thought I'd update my comment about "I wish the digital scopes had a Z input". It turns out that the Keysight scope I'm using does have blanking in X-Y mode - it is digital only (just on or off) and uses the trigger input. I guess it pays to actually...

That's probably why the memory test worked - at least the one Toshiba one that I have that is exactly like those passes the test on the FPGA tester. Thanks again for looking at this - it was a big help. Fred

Yes, from the looks of things the Z80 does not ever read the 4800-57FF memory except for when it clears the memory to 0 on startup (not a fan of MAME for actually playing games, but it's super nice for debugging and checking stuff like this). On everything I've seen, all the errors are ones...

Yes that's what I was looking for. Thanks a lot for checking it out. It definitely set me on the right track (details below) I tested a total of 3 boards and all had issues in this range but some were worse than others (some had only a couple of bits bad but some bits always worked). One of...

Has anyone done a memory test on pole position through the Z80 socket using a Fluke or similar? I'm working on the FPGA "cat box" tester Z80 interface and I've been fighting with getting all the PP RAMs to test through the Z80. The rams in the region 4800-57FF seem like I can write them through...

I've been working on Z80 testing for my FPGA tester and I came across this issue when working with Donkey Kong Junior. I also remember it being an issue when I tried a "standard" arcade switching power supply in the cabinet when my real one went out. Back then I put back a "real" nintendo...

Interesting - I'll have to try it again since I have that exact one.

I typically use an old analog oscilloscope for troubleshooting XY games on the bench and I have tested out several digital oscilloscopes (Tektronix, Rigol, and old HP) but nothing has been very useful in XY mode. I have a new Keysight DSOX1102 that is actually quite good (maybe not as good as...