Missile Command PCB - BAD MAP FF

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Getting BAD MAP FF in Test Mode. Does BAD MAP refer to the color RAM at L7 or the Address Decoding Circuit? Any thoughts/suggestions would be appreciated.

What is a B2S25 RAM anyway? Any equivilent?

Thanks.
 
Bad map refers to a problem in the bit-mapping hardware, likely a bad write-protect PROM (or bad socket) @ L6, 82S123. Also could be a problem in the Microprocessor Data Input Interface.

The 82S25 (cross: 7489,74S289BN,3101,27S02) RAM @ L7 is your color palette RAM, but that's not the problem.
 
Map bad 00

Necro bump. Since this is the only thread I could find on "bit map" error for missile command, figured why not.

Currently, I have the braze kit (error shows better) but the behavior is the same w/o it. Board was working fine for couple years and took a crap one day. Power supply is fine; I have it on bench and have replaced what appeared to be two bad roms and bad ram at N4 to get it back to this point.

Above comment reference prom at L6 but I can't even find that on schematic. Trying to figure out where to look on schematic. My logic, not saying much, tells me it has to be still related to data i/o of screen ram otherwise how would the cpu get results back to know something was wrong.

I am going to be probing around but could use some guidance. Thanks

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Necro bump. Since this is the only thread I could find on "bit map" error for missile command, figured why not.

Currently, I have the braze kit (error shows better) but the behavior is the same w/o it. Board was working fine for couple years and took a crap one day. Power supply is fine; I have it on bench and have replaced what appeared to be two bad roms and bad ram at N4 to get it back to this point.

Above comment reference prom at L6 but I can't even find that on schematic. Trying to figure out where to look on schematic. My logic, not saying much, tells me it has to be still related to data i/o of screen ram otherwise how would the cpu get results back to know something was wrong.

I am going to be probing around but could use some guidance. Thanks

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Bumping as I am also getting the BAD MAP 00 error on my MC Braze kit.

EDIT: L6 was socketed. New socket seemed to fix this.
 
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I figured I would bump again see if HudsonArcade or brzezicki can chime in?
 
Finally have my repro 6502 pod hooked up and am getting consistent errors when doing ram long tests to 3rd color bit ram region (0200-05FF) and 2-color-bit region

I am thinking it is not the ram as all 8 ram chips / data lines are used when testing the working ram<<most likely how the test code tests ram to begin with.

That leaves trying to figure out the dram address controller, madsel etc.. I think r/w to working ram is much simpler and only involves a couple chips. Damn this is going to be a learning process.
 
what are the exact Fluke results for each range?

-brian
Below are my results from running again after replacing socketed ram at N4 and H4 with TMS4116-20 to match what is on the board already. Read somewhere MC can be finicky with mismatched ram so figured I would try.

Results have been somewhat different every time. From bts errors to dcd errors to patt errors however, the working ram has been most consistent about being error free.

0000-01FFF 512B working ram - ram long = No Errors
2nd pass = No errors
0600-063F more working ram - ram long = No Errors
2nd pass
R/W err @ 0604 BTS 08 > cleared on loop
3rd pass = no errors

0200-05FF 3rd color bit ram - ram long = No Errors WTH?
2nd pass = No errors hmm.

06F0-3FFF 2 color bit ram - ram long =
DCD ERR @ 089C bit 0 > clears on loop
DCD ERR @ 1540 bit 7 > clears on loop
DCD ERR @ 1882 bit 6 > clears on loop
DCD ERR @ 1A77 bit 10 > clears on loop
DCD ERR @ 1C05 bit 5 > clears on loop
DCD ERR @ 2150 bit 5 > clears on loop
DCD ERR @ 2570 bit 12 > clears on loop
DCD ERR @ 2C40 bit 3 > clears on loop
DCD ERR @ 3126 bit 7 > clears on loop
DCD ERR @ 3339 bit 2 > clears on loop
PATT ERR @ 06FF > I hit cont before clearing on loop
PATT ERR @ 111F > eventually cleared on loop but I couldn't continue so stopped test.
2nd run didn't pay attention to DCD errors as they weren't same
got RAM PATT ERR @06FF looped and it cleared then errored again while looping

going to rerun on working ram and 3rd color
 
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I might be a masochist, jacklick, have this virus thing or all 3 but socketed every ram chip on the board. The ones I was able to extract whole (it was them or the board) tested fine. I tested every replacement 4116 in my neoloch as good and have exactly same symptoms as before, but getting some r/w bts errors. Will need to triple check all ram traces again before moving on.
damn this board is fragile.

I did discover or notice several caps are missing off the board at c24-c27. might not be related but on the to do list.

basically I am still leaning toward mushroom or madsel issues but figured I would update thread with non-progress.

Edit>>actually I wish i knew what the braze kit does but there is pal/gal labeled madsel so not sure if the problem is there. It has to bypass some of the address multiplexing. hmm I might try fluke through the braze kit.
 
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I definitely think it's one of the support circuitry//WP selects on the DRAM input probably not the DRAMs itself.

definitely though troubleshoot WITHOUT the braze kit. just bypass the whole thing plug directly in the CPU socket directly. if you are getting RAM errors there you know it's the PCB board (which is probably is)

I remember one really odd one I had where it was a bad resistor between the DRAM write enable lines between the OR gates (l5, k6) and the actual chip /WP lines...
I've never had a bad resistor cause CPU/memory issues before, (usually because resistors are usually not inline with the circuitry, but rather pull up/pull down) but in this case it was basically acting as a "cut" trace.

good luck.

-brian
 
I haven't given up on this and after repairing a different Missile Command, I started looking at this one again.

Been messing with it on and off today, reading, probing, scoping, compartoring and then found where klov member saltpetre fixed his bap map missile command.
https://forums.arcade-museum.com/showthread.php?p=4141498

I haven't found anything definitive yet but think my fluke results above were totally erroneous. I picked up a fluke 7201 accessory and now my results are much more consistent. No idea why but figured I would document and mention it.

Ram Patt err @ 09FF, 0BFF, 11FF, 13FF, 15FF, 17FF, 1BFF, 1DFF, 1FFF, 2BFF, 31FF, 33FF, 37FF, 3BFF all read 04 not FF or not 00. The errors were also not clearing on loop. The interesting thing is the consistency and area on screen all these represented. It was the furthest right pixel (FF?) and 04 was red vs FF(blue) or 00 (black).

04 is 0000 0100 in binary (my reference). anyway just documenting right now as I run fluke on my working board to make sure results are good/consistent.
 
Gonna bump this for another bad socket at L6.

Symptoms included crosshairs leaving choppy blue trails and the missile trails were jaggy and not straight. The scrolling words at the bottom became a scrolling black rectangle. Eventually it developed striped explosion graphics and striped "MISSILE COMMAND" word graphics, and others. In the end it became stuck randomly, and then developed resets. The self-test came back with MAP BAD 00. Reseating the PROM at L6 corrected the issues. Replaced the socket. All good now. Thanks all! :top:
 
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