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tzok

800XL sprites corrupted after 6 sec.

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I have a hardware problem with Atari 800 XL. In every game that uses sprites they got corrupted after about 6 sec. since initializing them. In SysInfo there is a sprite collision test and it works, but soon after it finishes, garbage occurs:

6058950300_1573911483_thumb.jpg

If I restart the test it works again fine.

 

In River Raid, sprites become small letters of alphabet and player graphics is a full screen height column of capital letters (letter depends on the vertical position on the screen, so moving sprites scroll vertically across the alphabet):

2789436200_1573911479_thumb.jpg

 

In Super Cobra it works for a while, but when it crashes for the first time, the heli crashes immediately after reappearing (it is a constant collision). In Pitfall II the demo doesn't scroll, and there is no character on the gamefield.

 

All games work for ~6 sec. and then garbage appears on the screen. If I reset computer it works again for same time, and in SysInfo it is enough to re run the test, so it is unlikely to be thermal issue.

 

I have swapped GTIA, RAM and OS ROM, but with no luck.

Edited by tzok

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Strange - it might be an Antic or MMU problem.  You can get the same result by putting Players onscreen then setting PMBASE so that it hits the character set ROM.

Obviously River Raid would have PMBASE set to somewhere in the first 16K of RAM so something's going badly wrong there.

 

Strange that programs loaded to memory don't just crash.  Can you try something like Shamus from disk (or other 16K Ram game) ?

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How was Sysinfo loaded?

 

Maybe try some other games, a mix of carts and disk loaded ones, especially with 32-48K Ram requirement.

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1 hour ago, Rybags said:

How was Sysinfo loaded?

 

Maybe try some other games, a mix of carts and disk loaded ones, especially with 32-48K Ram requirement.

I don't have much options... actually only thing I have is SIO2Arduino. I don't have much experience in 8-bit Atari, and I don't have much spares. I only have one other 8-bit Atari system, which is non-ECI 65XE. I swapped GTIA from it as it was socketed. In my 65XE merely no chips are socketed, while in 800XL all are.

 

I was informed that same effect occurs in River Raid when you change PMBASE to 0x00, instead of 0x08. Could it be a hint where to look for a fault?

Edited by tzok
update

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Could be a bad GTIA socket on the 800XL, could be the ANTIC ... just curious. If you boot to BASIC and let the system idle, do you get any graphical corruption? What about in the self-test (type BYE from the BASIC READY prompt).

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2 hours ago, DrVenkman said:

Could be a bad GTIA socket on the 800XL, could be the ANTIC ... just curious. If you boot to BASIC and let the system idle, do you get any graphical corruption? What about in the self-test (type BYE from the BASIC READY prompt).

Basic works just fine, selftest also. I hope to have another 800XL for tests tomorrow.

 

Didn't check the sockets, but they look ok. No visible corrosion on them.

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Yes swap Antic next (to a good machine not the other way around). Just in case... What power supply are you using? Have you checked voltages of the machine while its powered on? Chips can go bad from too much voltage. A good quality USB charger that supplies 1.5A or more will power the machine very well.

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2 minutes ago, Sugarland said:

Yes swap Antic next (to a good machine not the other way around). Just in case... What power supply are you using? Have you checked voltages of the machine while its powered on? Chips can go bad from too much voltage. A good quality USB charger that supplies 1.5A or more will power the machine very well.

I'm using 5V 3A Qoltec switching power supply. My 65XE works just fine on it.

Edited by tzok

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Whoever was betting on ANTIC was apparently right. Freezing ANTIC prior to starting computer vastly postpones occurring of the symptoms.

 

Strange is, it is not getting hot even without cooling.

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Maybe it's getting sufficiently warm for a pin or two to lose proper contact.  I'd think probably a high address bit - A15 and/or A14.

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13 hours ago, tzok said:

Shamus seems to work fine. So what - MMU?

Is that a modified Shamus? The original doesn't run on the XL or XE computers without the Translator.

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It does - you just have to hold a console key when the game's finished loading.

But in the context of this problem the 16K running version of the game is all that's needed.

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I have swapped ANTIC with another Atari and now I'm sure my ANTIC is faulty :(

PMBASE sets to 0x00 when it warms up.

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It already was socketed... I have swapped it back and forth, and the fault was always there, where the ANTIC from XL was.

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I have managed to buy a spare ANTIC in a right version/revision, and now my 800XL is fully functional again ;)

Thank you for your help.

 

P.S.

Would you suggest to keep XL OS rev.B, or upgrade it to XL OS rev.C (which was never factory installed in any 800XL)?

Edited by tzok
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It's Basic that had such revisions.  Rev C practically bug free where B is in many ways worse than A.

If you don't program in Basic yourself then it doesn't matter much.  The bugs tend to occur during program more than execution.

For all unmodified XLs it's a drop-in or solder in 8K Rom replacement.  Some very late XLs have Rev C as standard but it's pretty rare.

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Oh, I had BASIC rev. C from the beginning. I was asking for the XL OS. Stock one for XL was rev. 2 (or B), late 130XE, and 800XE had rev. 3 (or C). The obvious difference is Selftest, where finally you see 800XL/65XE keyboard layout, without 1200XL specific keys.

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