Missing sprites

[unixdude]

Today I finished up my SCCC install (video is now routed through the 800's onboard monitor port), and now as I check it out, I see sprites missing from games. I remember reading about that somewhere, but as I look for it now, I can't find it.

 

Do missing sprites indicate a dead/dying GTIA chip?  Something else?

 

As an example: in Pac-Man, the pac-man himself and the ghosts are all invisible. The pellets and board are visible, and pellets disappear as the Pac-Man eats them. In Pole Position, the cars are missing.

The missing sprite issue doesn't happen in all games -- in Joust, everything looks good most of the time -- for a few seconds, the player sprite did show onscreen three times (simultaneously), but then 2 disappeared. Anyway, something's going on here. Any ideas about what it could be?

 

Thanks.

[Rybags]

Try prying up and reseating Antic and GTIA.

Possibly GTIA isn't getting the /HALT signal which it uses as a trigger to read PM graphics from the data bus.

In the cases where sprites appear normal it's likely that the CPU is loading the graphics registers itself.

 

Another thing to try is put another Antic and GTIA in - if the problem remains then the board probably has a fault.

You could also try running a jumper wire from the Halt pin of Antic or the CPU to the one on GTIA.

[+Stephen]

Here's a program I wrote in BASIC to help diagnose PM/G issues when I built my 1088XEL.  What it should look like, is 4 columns of the 2600 Space Invaders graphics, each column a different colour, and they will cycle from left to right.

pmgtest.bas

[unixdude]

I also have an Incognito in this 800. I wonder if I didn’t solder the halt line well to the SCCC. I’ll check that. Thanks!

[unixdude]

Well, I have confirmed the soldering of the halt and ready pins to the SCCC. I have reset the ANTIC and GTIA chips. No change. 😥

 

I’ll try that program. Thanks. 

[unixdude]

2 hours ago, Stephen said:

Here's a program I wrote in BASIC to help diagnose PM/G issues when I built my 1088XEL.  What it should look like, is 4 columns of the 2600 Space Invaders graphics, each column a different colour, and they will cycle from left to right.

pmgtest.bas 916 B · 4 downloads

Super newbie question... how do I get this onto my 800?  I'm just now resuming this Atari Incognito project after many months of idling on it, and I don't know how to do it.  I'm sure there's a way to build an ATR file on my iMac, but I haven't found it yet.

 

I have a CF card in my Incognito, but right now I'm trying to figure out how to format it such that it can be used on both the Incognito and the Atari. I know FJC has docs on this, but I haven't found them yet, and I don't have it sorted yet.  Also, I have an SDrive-MAX at my disposal.

 

Any guidance here would be appreciated.  Thanks.
 

-----

 

I got the file loaded onto my 800, and the attached pic is what I get when I run the program.  There's no cycling, it just prints this one thing and then stops (note the "READY" prompt here, which is after running the program).

 

This was run with my Incognito in XL/XE mode, with BASIC enabled.  I went and ran it in Colleen mode using some BASIC (not sure if it was my cartridge or the Incognito's onboard BASIC), and got the same result.

Edited March 22, 2020 by unixdude
Edited to show result; I figured out how to load the program

[+Stephen]

30 minutes ago, unixdude said:

Super newbie question... how do I get this onto my 800?  I'm just now resuming this Atari Incognito project after many months of idling on it, and I don't know how to do it.  I'm sure there's a way to build an ATR file on my iMac, but I haven't found it yet.

 

I have a CF card in my Incognito, but right now I'm trying to figure out how to format it such that it can be used on both the Incognito and the Atari. I know FJC has docs on this, but I haven't found them yet, and I don't have it sorted yet.  Also, I have an SDrive-MAX at my disposal.

 

Any guidance here would be appreciated.  Thanks.
 

-----

 

I got the file loaded onto my 800, and the attached pic is what I get when I run the program.  There's no cycling, it just prints this one thing and then stops (note the "READY" prompt here, which is after running the program).

 

This was run with my Incognito in XL/XE mode, with BASIC enabled.  I went and ran it in Colleen mode using some BASIC (not sure if it was my cartridge or the Incognito's onboard BASIC), and got the same result.

Darn it.  It seems I have attached an incorrect program.  Stand by, I will try to find what I was looking for.

PMG.BAS

 

OK - verified this was the correct one.

[unixdude]

Thanks. The very first time this ran through the cycle, P0 was not visible until it started moving.  P1, P2, and P3 were all visible as they were being drawn.  In subsequent cycles of the same execution, P0 was visible as it was being drawn. What does this point to?

 

Edit: I ran it again (after power cycling the machine and trying my Pole Position cartridge again), and this time, P0 was visible as it was being drawn.  Pole Position still does not work correctly.

Edited March 22, 2020 by unixdude

[+Stephen]

I'm way more of a software guy than a hardware guy, but if the machine was mine, I would 1st try another GTIA chip, then the ANTIC.  The issue that was eventually covered when I was beta testing the 1088XEL was the PAL system needed a different buffer chip (I think a 74HCT08 was changed to a 74F08).  I do not think the 800 has the exact same circuitry as the 1088XEL was a 100% new PCB layout.

[unixdude]

Turned out to be a bad GTIA.  I took the GTIA from my other Atari 800 and inserted it into this one, and now the PMGs appear.  Attached pictures are of my working system (yes, I temporarily installed some electrical tape to hold the power cutoff switch), the screen showing Pac-Man and all PMGs, the donor card, and the bad chip. Please don't comment on my amateur install here.  

 

I'm pretty excited about the outcome here.  Thanks to all who helped.

[unixdude]

Question bout the Pac-Man board: Should it be dotted like that?  I thought it would be more solid.  The pic attached to this comment is from my second 800, the one that displays only black & white for some reason (I'd love to get that fixed too).  This is using the GTIA chip that wasn't showing PMGs in the SCCC 800, so maybe the GTIA chip wasn't the problem -- note that all the PMGs are visible here.

 

Also note that the board is solid, not "dotted" like the blue one above.

 

Any ideas what might be going on here?

Edited March 22, 2020 by unixdude
Clarification, and fix typo

[unixdude]

I replaced the ANTIC on my SCCC/Incognito 800 with the one from my "donor 800," and the dotted blue lines still appear in Pac-Man.  I don't remember them before, but maybe I wasn't paying enough attention.

[_The Doctor__]

no color, make sure it's the correct tv system,

double check color/tint potentiometer and cable.

check solder joints to monitor jack on the Atari.

check caps and the usual chips

after that color burst frequency etc.

[jamm]

Someone else just asked the same question about the dotted pattern in the Pac-Man maze:

 

[+DrVenkman]

47 minutes ago, unixdude said:

I replaced the ANTIC on my SCCC/Incognito 800 with the one from my "donor 800," and the dotted blue lines still appear in Pac-Man.  I don't remember them before, but maybe I wasn't paying enough attention.

The “dots” are an artifact of how your flat-panel display is interpreting the signal. Connect to a CRT and you won’t see them. 

[+Faicuai]

33 minutes ago, DrVenkman said:

The “dots” are an artifact of how your flat-panel display is interpreting the signal. Connect to a CRT and you won’t see them. 

This is not true.

 

My SONY Wega 32" CRT (with tons of bandwidth and vertical/hor. resolution) showed dot-crawl from my Atari's composite output, left and right.

 

A bandwidth-constrained CRT, however, may be different...

[_The Doctor__]

do the resistor mod, l-c levels may be off. The 800 has a nice output, but Atari has been know to use what's close enough and on hand through out it's production runs in certain areas.

You can get these same affects when doing luma/chroma/audio on most Atari's and certain monitors. Some monitors have filters using a myriad of names that are adjustable. some have full control others have low med high, aggressive etc.

I'd check everything the monitor has to adjust mark where normal is, and then adjust them one at a time for the best picture characteristics.... after that, I'd combine all the best setting together.

 

*** I do see tearing around the ghost box in your color picture *** this is not normal *** so another issue is at play.

 

certain cables combine composite with the luma or chroma causing similar effects on some tv/monitors

 

Atari planned their video around worst cast television of the era with crappy cables. This made some issues... I think people should have had their televisions adjusted or repaired myself, and Atari should have used the full number of columns and rows that would fit the actual display paramters rather than setting the cursor two spaces to the right etc etc...

+++ this fudging made certain tv/monitors look terrible later on as better cables and television arrived, certain NEC monitors took all of this into account and made some beautiful displays.

 

Edited March 22, 2020 by _The Doctor__

[unixdude]

12 hours ago, jamm said:

Someone else just asked the same question about the dotted pattern in the Pac-Man maze:

 

THANK YOU for this link!  In that thread, user Faicuai mentioned that the issue could be related to using composite output instead of s-video output.  I changed to S-video (fortunately my TV has an S-video input), and BOOM, my display issues disappeared, at least for Pac-Man.  I'll try other games tomorrow, but I think this project might now be complete!  I'll test more tomorrow night, then reassemble.

 

And, I need to figure out how to best clean my 800 case... Not sure retrobriting is the right thing for an 800 case which intentionally has multiple colors on it.

[_The Doctor__]

switching to a luma chroma cable (svideo) always a good choice!