bigral Posted June 12, 2018 Share Posted June 12, 2018 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? Quote Link to comment Share on other sites More sharing options...
jaybird3rd Posted June 12, 2018 Share Posted June 12, 2018 I had a similar issue with an XEGS of mine. Replacing ANTIC fixed it for me. Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted June 12, 2018 Share Posted June 12, 2018 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... Quote Link to comment Share on other sites More sharing options...
Rybags Posted June 12, 2018 Share Posted June 12, 2018 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. 1 Quote Link to comment Share on other sites More sharing options...
bigral Posted June 12, 2018 Author Share Posted June 12, 2018 (edited) 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. Edited June 12, 2018 by bigral Quote Link to comment Share on other sites More sharing options...
+Nezgar Posted June 12, 2018 Share Posted June 12, 2018 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? Quote Link to comment Share on other sites More sharing options...
bigral Posted June 12, 2018 Author Share Posted June 12, 2018 (edited) 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.staticflickr.com/2/1726/41861842465_29b0013716_b.jpg and https://c1.staticflickr.com/2/1724/42044851344_83ac4743c7_b.jpg ... but still it works fine with memory test and on startup when computer still cold Edited June 12, 2018 by bigral Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted June 12, 2018 Share Posted June 12, 2018 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. 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted June 13, 2018 Share Posted June 13, 2018 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. Quote Link to comment Share on other sites More sharing options...
RickR Posted June 13, 2018 Share Posted June 13, 2018 Failing power brick would be my first suspect. Quote Link to comment Share on other sites More sharing options...
1050 Posted June 13, 2018 Share Posted June 13, 2018 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. Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 13, 2018 Share Posted June 13, 2018 Hit the chips with some freeze spray and see if you can make the problem go a away 1 Quote Link to comment Share on other sites More sharing options...
Rybags Posted June 13, 2018 Share Posted June 13, 2018 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. Quote Link to comment Share on other sites More sharing options...
Sugarland Posted June 13, 2018 Share Posted June 13, 2018 Have you tried a different power supply? That might be the issue. Quote Link to comment Share on other sites More sharing options...
bigral Posted June 13, 2018 Author Share Posted June 13, 2018 (edited) 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 June 13, 2018 by bigral Quote Link to comment Share on other sites More sharing options...
bigral Posted June 14, 2018 Author Share Posted June 14, 2018 UPDATE: glitch disappeared after removing metal casing (upper that rests between pc board and keyboard). Quote Link to comment Share on other sites More sharing options...
shoestring Posted June 14, 2018 Share Posted June 14, 2018 That's weird. Quote Link to comment Share on other sites More sharing options...
JR> Posted June 14, 2018 Share Posted June 14, 2018 That can help with heat related problems. Quote Link to comment Share on other sites More sharing options...
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