42 replies to this topic

[AtariLeaf]

I was playing choplifter and noticed a row of bars at the top of the screen (as seen in the picture) and wondered what they were. I tried 2 other 7800's and those bars weren't there. None of the 3 7800's I tried had the expansion port and I'm not sure which version of 7800 it is that is causing this particular glitch but a picture of the label is below as well.

I couldn't find any info on this particular glitch here at AA, just one about the graphics reverting to a sort of 2600 look after playing for a bit but that is not what this is. Anyone know what this is and what might be causing it?

Attached Thumbnails

• 
• 

[AtariLeaf]

Bump. Anyone have any ideas?

BTW, all other 7800 games seem to work fine on said console with no bars at the top of the screen. Just choplifter, but the choplifter cart seems to be fine on other 7800 consoles. Go figure.

[frunobulax]

AtariLeaf, on Sun Oct 24, 2010 5:53 PM, said:

Bump. Anyone have any ideas?

BTW, all other 7800 games seem to work fine on said console with no bars at the top of the screen. Just choplifter, but the choplifter cart seems to be fine on other 7800 consoles. Go figure.

Mine also does the same thing with the bars.


After a while of playing (or some times right away) the graphics will glitch out where everything is only half as wide as it should be, and the colors of the sprites go all weird. That's the second image.. I forgot to turn the flash off when I took it though.

Attached Thumbnails

• 
• 

[AtariLeaf]

I've read about that second picture, there's a thread on that here: http://www.atariage...._hl__choplifter

I haven't had that yet, just the bars. I'll leave it on a while and see if it happens.

[GroovyBee]

The "half width" looks like the video mode has changed from 160A to 160B. Does this happen in the emulator? I don't play Choplifter much on my 7800. Writing junk to the Display List will cause a variety of problems including "half width" and the bars above.

[AtariLeaf]

GroovyBee, on Mon Oct 25, 2010 7:20 AM, said:

The "half width" looks like the video mode has changed from 160A to 160B. Does this happen in the emulator? I don't play Choplifter much on my 7800. Writing junk to the Display List will cause a variety of problems including "half width" and the bars above.

If you read that thread I linked above, some people are saying that it does indeed happen in the emulator.

As an update, I let choplifter run for an hour on this machine and didn't experience the glitching, just the bars along the top. All other games work fine on this machine, no bars, and this choplifter runs fine with no bars on other 7800's. Very weird.

[GroovyBee]

AtariLeaf, on Mon Oct 25, 2010 8:01 AM, said:

If you read that thread I linked above, some people are saying that it does indeed happen in the emulator.

If it happens in the emulator its a software bug and not marginal hardware.

[AtariLeaf]

GroovyBee, on Mon Oct 25, 2010 7:20 AM, said:

The "half width" looks like the video mode has changed from 160A to 160B. Does this happen in the emulator? I don't play Choplifter much on my 7800. Writing junk to the Display List will cause a variety of problems including "half width" and the bars above.

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

[GroovyBee]

AtariLeaf, on Mon Oct 25, 2010 8:22 AM, said:

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

If the emulator does it too its a software problem. A common cause of "writing junk" would happen when a 6502 memory pointer becomes corrupted. This could be due to a variety of reasons.

[AtariLeaf]

GroovyBee, on Mon Oct 25, 2010 8:29 AM, said:

AtariLeaf, on Mon Oct 25, 2010 8:22 AM, said:

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

If the emulator does it too its a software problem. A common cause of "writing junk" would happen when a 6502 memory pointer becomes corrupted. This could be due to a variety of reasons.

Well apparently the newer emulators don't do it. But the thread I posted is from 2004 and versions of MESS from that time seemed to cause the exact same problem. One person said he had several copies of choplifter and several 7800's and it happened on all of his carts and systems.

I wonder if its certain copies of the game combined with certain revisions of 7800 hardware, which was why I posted the back label with model and serial numbers in the original post.

I wish I had a second copy of choplifter to try, it would help to possibly narrow this down.

Edited by AtariLeaf, Mon Oct 25, 2010 8:37 AM.

[frunobulax]

I don't know if it's real clear in my pictures I posted, but if you notice, the black bars at the top go away after the half width glitch begins.

[AtariLeaf]

frunobulax, on Mon Oct 25, 2010 10:04 AM, said:

I don't know if it's real clear in my pictures I posted, but if you notice, the black bars at the top go away after the half width glitch begins.

Do you happen to have a second system to try your copy on or do you happen to have a second copy of choplifter to see if this happens?

[GroovyBee]

frunobulax, on Mon Oct 25, 2010 10:04 AM, said:

I don't know if it's real clear in my pictures I posted, but if you notice, the black bars at the top go away after the half width glitch begins.

That tells me there is more than one instance of corruption occurring in the display list for the first zone.

[frunobulax]

AtariLeaf, on Mon Oct 25, 2010 10:05 AM, said:

frunobulax, on Mon Oct 25, 2010 10:04 AM, said:

I don't know if it's real clear in my pictures I posted, but if you notice, the black bars at the top go away after the half width glitch begins.

Do you happen to have a second system to try your copy on or do you happen to have a second copy of choplifter to see if this happens?

Not yet >

Here is a photo of my label. BTW: the system has No expansion port, and no indication of a cut out on the shell. I removed the RF modulator and added a composite video mod (which is what is used to make the pictures I posted), but it did the same thing through the normal RF.

Attached Thumbnails

• 

[frunobulax]

GroovyBee, on Mon Oct 25, 2010 8:29 AM, said:

AtariLeaf, on Mon Oct 25, 2010 8:22 AM, said:

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

If the emulator does it too its a software problem. A common cause of "writing junk" would happen when a 6502 memory pointer becomes corrupted. This could be due to a variety of reasons.

I'm starting to wonder what kind of reasons... I don't know near enough about the 7800 processor to begin to think of any myself. Are people saying that the 'half width' thing also happens in the emulator?

Perhaps there is a certain rom version that interacts with a certain hardware version and this was the hardware version that was emulated thus showing the glitch? Does that make *any* sense? lol! I don't know near enough about this particular hardware to even guess at this point.

[AtariLeaf]

frunobulax, on Mon Oct 25, 2010 1:44 PM, said:

GroovyBee, on Mon Oct 25, 2010 8:29 AM, said:

AtariLeaf, on Mon Oct 25, 2010 8:22 AM, said:

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

If the emulator does it too its a software problem. A common cause of "writing junk" would happen when a 6502 memory pointer becomes corrupted. This could be due to a variety of reasons.

I'm starting to wonder what kind of reasons... I don't know near enough about the 7800 processor to begin to think of any myself. Are people saying that the 'half width' thing also happens in the emulator?

Perhaps there is a certain rom version that interacts with a certain hardware version and this was the hardware version that was emulated thus showing the glitch? Does that make *any* sense? lol! I don't know near enough about this particular hardware to even guess at this point.

I'm starting to think that its a certain revision of 7800 hardware that causes this. You would think other games would be affected in some way if there was something wrong with the machine and again, my choplifter works just fine on other 7800's. Its not completely crazy. According to the FAQ, Food Fight will lock up on certain revisions of the 7800.

I don't think anyone really knows for sure. I've heard talk of timing issues but again, you'd think other games would be affected but none apparently are. Very strange.

Edited by AtariLeaf, Mon Oct 25, 2010 1:51 PM.

[frunobulax]

AtariLeaf, on Mon Oct 25, 2010 1:49 PM, said:

frunobulax, on Mon Oct 25, 2010 1:44 PM, said:

GroovyBee, on Mon Oct 25, 2010 8:29 AM, said:

AtariLeaf, on Mon Oct 25, 2010 8:22 AM, said:

BTW, what would cause this "writing junk" you're talking about. Is this a hardware issue? Still seems strange to me that old versions of emulators emulated a hardware problem.

If the emulator does it too its a software problem. A common cause of "writing junk" would happen when a 6502 memory pointer becomes corrupted. This could be due to a variety of reasons.

I'm starting to wonder what kind of reasons... I don't know near enough about the 7800 processor to begin to think of any myself. Are people saying that the 'half width' thing also happens in the emulator?

Perhaps there is a certain rom version that interacts with a certain hardware version and this was the hardware version that was emulated thus showing the glitch? Does that make *any* sense? lol! I don't know near enough about this particular hardware to even guess at this point.

I'm starting to think that its a certain revision of 7800 hardware that causes this. You would think other games would be affected in some way if there was something wrong with the machine and again, my choplifter works just fine on other 7800's. Its not completely crazy. According to the FAQ, Food Fight will lock up on certain revisions of the 7800.

I don't think anyone really knows for sure. I've heard talk of timing issues but again, you'd think other games would be affected but none apparently are. Very strange.

With my luck, I probably have a combination of hardware glitch with the 7800 (bars) and software glitch with my version of choplifter (half-witch). Typical... Hahaha!

[AtariLeaf]

Well the one that's giving me the bars is a non-expansion port 7800. On the label right beside the "A3" in the middle, it has stamped in a purplish color "9 B 1". Not sure you can make it out in the picture in the original post. Can this revision be identified with this number?

[GroovyBee]

@AtariLeaf: Do you have a CC2? I'll code up a RAM test when I get some spare time and then you'll be able to run it for a few hours to see if it shows any problems up.

[AtariLeaf]

GroovyBee, on Mon Oct 25, 2010 4:38 PM, said:

@AtariLeaf: Do you have a CC2? I'll code up a RAM test when I get some spare time and then you'll be able to run it for a few hours to see if it shows any problems up.

No sorry I don't have a cuttle cart 2. Thanks for the help though. You think this is a ram issue?

[AtariLeaf]

I went and tried a bunch of games with this particular 7800:

Ace of Aces
Super Huey
Tower Toppler
Ball Blazer
Karateka
Pole Position II
Hat Trick

I saw no glitchiness with any of these games. Is there something special about Choplifter, software wise or the way it interacts with the console that is different from all these other games?

[GroovyBee]

I suspect that its just a plain old software bug. It'd be nice to dump the offending cart to compare against.

[FireTiger]

I have this problem, one cart and one console I have a post of it. I got another cart and the new cart works, the CC2 works perfectly on the same console.

http://www.atariage....__1#entry682422

Edited by FireTiger, Sat Oct 30, 2010 6:06 PM.

[AtariLeaf]

FireTiger, on Sat Oct 30, 2010 6:03 PM, said:

I have this problem, one cart and one console I have a post of it. I got another cart and the new cart works, the CC2 works perfectly on the same console.

http://www.atariage....__1#entry682422

I believe yours was the post I was referrencing too. Did you have those bars at the top of the screen or just the glitch where it looked like it dropped to 2600 mode?

[FireTiger]

AtariLeaf, on Sat Oct 30, 2010 7:04 PM, said:

FireTiger, on Sat Oct 30, 2010 6:03 PM, said:

I have this problem, one cart and one console I have a post of it. I got another cart and the new cart works, the CC2 works perfectly on the same console.

http://www.atariage....__1#entry682422

I believe yours was the post I was referrencing too. Did you have those bars at the top of the screen or just the glitch where it looked like it dropped to 2600 mode?

Mine didn't do the bars at the top - unless I didn't notice, just dropped into 2600 mode with the funky graphics and the wide split in the middle- the CC2 on the same machine works fine... in the end found a new choplifter cart and used it- if I can find my 'bad' cart and get the glitch to reproduce (requires an bad cat ~and~ a bad 7800 as far as I can tell) I'm willing to send the bad cart to whoever wants to check its code.

(the lucky person can keep the stupid thing too...)

Edited by FireTiger, Tue Nov 2, 2010 3:06 AM.