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65XE garbage appears on map of BoulderDash1 after warm up


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#1 bigral OFFLINE  

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Posted Tue Jun 12, 2018 4:11 AM

Hello, I'm new to Atari 8bit H/W, so I wonder why garbage may appear on the map of BoulderDash1 levels after 30..40min playing the game. Internal memory test show nothing special. I have replaced DRAMs, tried OKI, FUJI, MOS (all 150ns), no change! I guess changes happen in video memory because otherwise game would hang. Is this an ANTIC\CPU address bus clash issue?



#2 jaybird3rd OFFLINE  

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Posted Tue Jun 12, 2018 6:29 AM

I had a similar issue with an XEGS of mine.  Replacing ANTIC fixed it for me.



#3 Nezgar OFFLINE  

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Posted Tue Jun 12, 2018 8:26 AM

I have an ANTIC chip that seems to show random 'snow' type interference, (random white dots) but only on some games - Encounter! Seems to exhibit it the most prominently. Not really 'garbage' per se, so maybe not as severe as you are seeing...

#4 Rybags OFFLINE  

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Posted Tue Jun 12, 2018 8:57 AM

That can be due to other things.  When I had the 32in1 OS installed I'd get random glitches in characters.  Supposedly the problem can be due to Phi2 timing issues and also due to certain sequences of Ram/Rom accesses where one or the other puts residual data on the bus for too long.



#5 bigral OFFLINE  

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Posted Tue Jun 12, 2018 1:45 PM

OK, I have replaced ANTIC, no effect, still garbage on the screen after ~30..40 min of playing. Also I have tried another SALLY, and result: RED SCREEN and no run (doesn't work at all), however I'm not sure if this SALLY was working before, no other machine to check.

 

41860198575_748ab3a729_c.jpg


Edited by bigral, Tue Jun 12, 2018 1:52 PM.


#6 Nezgar OFFLINE  

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Posted Tue Jun 12, 2018 1:59 PM

OK, thats a very different issue than mine I was describing...

How about with other games? I wonder if the game itself is corrupt.

At this point, if you purely just reboot the computer does it happen immediately again or take another 30-40 mins?



#7 bigral OFFLINE  

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Posted Tue Jun 12, 2018 3:34 PM

yes, after warm up you may do reload game and glitch will go right away, I found that R/#W signal rather BAD... see photos: https://c1.staticfli...9b0013716_b.jpg and https://c1.staticfli...3ac4743c7_b.jpg ... but still it works fine with memory test and on startup when computer still cold


Edited by bigral, Tue Jun 12, 2018 3:35 PM.


#8 DrVenkman OFFLINE  

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Posted Tue Jun 12, 2018 3:58 PM

I have a 1200XL that had a bad GTIA - it would run fine for about 10 - 15 minutes when cold but then graphical glitches showed up all over the place. Replacing the GTIA fixed it. 



#9 Rybags OFFLINE  

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Posted Tue Jun 12, 2018 7:55 PM

IMO very likely not a GTIA problem.

 

Boulder Dash it appears doesn't use PM graphics, so those glitches with Rockford are actully character stores gone awry.

The game uses 80 bytes of seperation betwen each character line so the "half Rockford" under and to the left is either 154 or 158 characters ahead of where it should be (can't work out who's the proper Rockford).

That doesn't really correlate to something like a sticking address bit which would usually give an offset of a power of 2.

 

It's hard to say what's going wrong - it might just be memory corruption causing the program to be altered.  Might be something else.

 

Maybe try something like this in Basic.  Then give it the same 30-40 minutes:

 

10 GR. 8 : SE. 2,0,0

20 C = NOT C : C. C

30 F. Y = 0 TO 191 : F. X=0 TO 319 : PLOT X,Y : N.X : N.Y

40 GOTO 20

 

That'll slowly fill the screen with solid colour then back to blank.  But it's doing a bit of variable memory access so might be able to reproduce the problem.

 

Note that 6502 is never really in a halted state - it accesses memory on practically every cycle (ignoring WSYNC and DMA states) so an inactive system isn't really like that but generally the variation of memory accesses will be less.



#10 RickR OFFLINE  

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Posted Tue Jun 12, 2018 10:34 PM

Failing power brick would be my first suspect. 



#11 1050 OFFLINE  

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Posted Wed Jun 13, 2018 1:16 AM

That can be due to other things.  When I had the 32in1 OS installed I'd get random glitches in characters.  Supposedly the problem can be due to Phi2 timing issues and also due to certain sequences of Ram/Rom accesses where one or the other puts residual data on the bus for too long.


I always change out U18 74LS08 for 74HCT08 every
chance I get and my babies seem to love me for it.
Randomness in screen characters goes away, I like
to think it's because of the more square Phi2 clock
but I don't have a means to look at it yet. I can
swap out a chip though. It's not a common problem
of mine, but I have seen it several times. MMU
might be involved too, this sort of smells like
the CPU at the same time especially the warm up
time part. At least that's my take on it.

#12 shoestring OFFLINE  

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Posted Wed Jun 13, 2018 3:32 AM

Hit the chips with some freeze spray and see if you can make the problem go a away 



#13 Rybags OFFLINE  

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Posted Wed Jun 13, 2018 4:29 AM

After seeing the screenshot, it's clear that it's not a glitch like the one I described.  It does appear to be spurious stores going to Ram so I would clear GTIA of suspicion but put the CPU, Antic, Ram and memory select logic in the suspect list.



#14 Sugarland OFFLINE  

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Posted Wed Jun 13, 2018 11:23 AM

Have you tried a different power supply?  That might be the issue.



#15 bigral OFFLINE  

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Posted Wed Jun 13, 2018 3:43 PM

I'm using regulated power supply taken from mac lc rated as 4.5A on 5v. Voltage = 5.01V constantly. Replaced GTIA, no effect. Replaced 74ls08 with 74f08 no effect. Replaced MMU (PAL16L8 (?)), no effect. Replaced all stabilizing capacitors on DRAM chips, no effect. Added 1K resistor from 5V to 1 pin of 74f08 to make clock signal better. Added 220pf capacitor to R/#W signal to get rid of HALF 0 HALF 1... no effect.

 

I think I have defective Sally... but it works good at the start. :( I don't have replacement of Sally for the moment.

 

About, temperature of chips, well they are warm, I think all with same temperature.


Edited by bigral, Wed Jun 13, 2018 3:47 PM.


#16 bigral OFFLINE  

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Posted Thu Jun 14, 2018 2:16 PM

UPDATE: glitch disappeared after removing metal casing (upper that rests between pc board and keyboard).



#17 shoestring OFFLINE  

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Posted Thu Jun 14, 2018 3:00 PM

That's weird.



#18 JR> OFFLINE  

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Posted Thu Jun 14, 2018 3:24 PM

That can help with heat related problems.






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