Is there EASY test for BAD GTIA in late model XE (China)

[+wood_jl]

As you know, there were some XE computers put out with "buggy" GTIA chips toward the end of the production run. From what little I am able to find, they were made in China. If you look on the B & C Computervisions site in the price list for 8-bit computers, they even have some PAL 130XEs that they list as "fails GTIA test."

 

http://www.myatari.com/atarixlh.txt

 

From that page:

 

We have a group of brand new in the box 130XE PAL computers

that have a different OS ROM and do not pass the GTIA test

for some reason?? They work fine with many games but since the

GTIA grapics mode does not work games like Recue on Fractalus

look weird. These are brand new but Atari did not include

manuals or powerpacks and they do not have a label on the bottom.

HDA008G COMPUTER PAL B 130XE 60.00 do not pass GTIA test?

HDA008IG COMPUTER PAL I 130XE 60.00 do not pass GTIA test?

 

 

 

I have seen reference to this problem on some other sites, like in the body of text of this site where he addresses the problem in the description of his 1Mb memory upgrade:

 

http://www.holyoak.com/atari/memsch1.txt

(the "front page" of his Atari site is http://www.holyoak.com/atari/ )

 

From the body of his text file from the site above:

 

"Some (if not most) of these 800XE/65XE's had a buggy GTIA (made in China)."

 

(1) Any idea how many machines may have had this problem? I wonder if it was just one bad run, or over time. The affected machines listed on B&C obviously say they're PAL. The Guy's site with reference to 800XE suggests he's in Europe as well but I'm not able to tell DEFINITIVELY where he is or exactly which units he's worked on.

 

(2) Is this problem likely confined to PAL zones? Should I be afraid of NTSC 130XEs made in China now? I sort of am.

 

(3) If anybody has dealt with this problem before, is "merely" replacing the GTIA chip a likely fix or could this involve more components?

 

(4) Would there be an easy test for this? I know booting up Rescue on Fractalus (as mentioned at B&C) will test it, but how about something easy to have an Ebay seller try it.

 

Waaaay back in the day I had my early model Atari 400 upgraded. I remember reading in the magazine to enter in BASIC

10 GRAPHICS 9

20 GOTO 10

 

.....and running it would tell you which you had - flickery blue screen=CTIA, black screen=GTIA. I wonder if this would diagnose the bad GTIA.

 

I don't suppose I'd have much luck getting an Ebay seller to type that into BASIC, but one can hope, if they're honest, cooperative, and especially if they're familiar with A8s. Maybe just avoid CHINA models, or is this a smaller problem that I think it is? Damn, and just when I was kinda looking for another 130XE to think about getting modded.

 

I checked my (Ebay sourced) unit that works fine, and it's a TAIWAN model of course.

Edited September 9, 2008 by wood_jl

[Rybags]

I don't know what the extent of the problem was and if it was limited to certain manufacturing locations of batches of machines.

 

I've not seen a proper symptoms list, but I've read about:

 

- collision detection not working properly (or at all).

Such a condition would affect an enormous percentage of games.

 

- Graphics 10 pixels not shifted to the right by 1 colour clock.

Such a condition would make some graphics modes like TIP not work properly.

A bit harder to test for, but there are countless demos, pictures about which could verify it.

 

The quickest way to check if a GTIA is installed (as opposed to CTIA) is just POKE 623,64 at the READY prompt - screen should go black and the text go blocky for GTIA.

[Rybags]

Here we go, it seems Wiki might have the answer http://en.wikipedia.org/wiki/George%27s_Te...terface_Adapter

 

Atari XE computers made for the Eastern European market were built in China. Many if not all have a buggy PAL GTIA chip. The luma values in Graphics 9 and higher are at fault, appearing as stripes. The only solution is to replace the chip.

 

If that is the case, then a colour graduation test would quickly root out the bad ones.

 

Something like:

 

10 GR. 9:D=1:FOR X=0 TO 79
20 COLOR C:C=C+D:IF C=15 OR C=0 THEN D=-D
30 PLOT X,0:DR. X,191
40 NEXT X
50 G. 50

 

Will give, on a healthy system:

[+wood_jl]

Thanks so much, Ryabags for your informative reply.

 

This still begs the question, then:

 

IF I FIND A 130XE IN THE UNITED STATES THAT SAYS "MADE IN CHINA," DOES IT MEAN IT'S A PAL MACHINE???

 

I've seen some for sale that said CHINA.

 

I'm still confused on that issue. Anybody seen a Yankee 130XE from CHINA??

 

THanks.

[Sikor]

You can download ssinfo from Drac030 web page: http://drac030.krap.pl/en-inne-pliki.php - in this stuff you can find many tests for Atari hardware...

[Marius]

Thanks so much, Ryabags for your informative reply.

 

This still begs the question, then:

 

IF I FIND A 130XE IN THE UNITED STATES THAT SAYS "MADE IN CHINA," DOES IT MEAN IT'S A PAL MACHINE???

 

I've seen some for sale that said CHINA.

 

I'm still confused on that issue. Anybody seen a Yankee 130XE from CHINA??

 

THanks.

 

I'm not sure, but I have over 30 of these XE's but these are all 64KB machines. It is the 800XE and the 65XE. I'm wondering if there really are 130XE's with the same problem... And since it is obviously a bug, I hardly can imagine that this bug also exists in a NTSC GTIA.

 

And... the last thing to say: I have replaced a lot of those buggy GTIA's ... It is not a nice job (because of the bad condition of these XE mainboards) but with the right tools it's a 'do-it-yourself' job.

 

With the GTIA replaced it works fine. But again: If it is a NTSC machine, I think you will not have this problem.

 

Marius

 

p.s. I might be wrong, but I think a PAL machine is more compatible with modern software. The collision problem mentioned in a post above in this thread is not my experience btw.

[Rybags]

So what is the exact problem. Is it only with Gr. 15 extra luminence values, or are there other things that don't work properly?

[Marius]

In fact everything works but what you see is not what you want to see. In GTIA modes the shades are not working right. So in stead of the beautifull shades (like in Graphics 9) you see a strange square pattern. Some XE's have this problem more than others. Some of the squares in the pattern are blinking (not on all XE's) ... very strange problem.

 

If have been looking over this problem for a long time, and as far as I see it right, it is more like a timing problem, which can be fixed, also without a better GTIA. there is a Fix available (with a few TTL's I guess) but the fix is not 100%.

 

My 'modest' opinion is that these eastern-europe XE's deal with timing problems (besides the GTIA bug) ... I have had more troubles with them, and the graphics output is -even when fixed with a good GTIA- not as good as expected. Some xe's are better than others.

 

I have had timing trouble with these XE's with blackbox too. There are so many variations of main boards. Some with 8x 1bit memory chips. Some with 2 * 4 bit memory chips. Some with a common (standard) 6502, some with a real Atari brand 6502. The quality of the components printboard and especially the solder contacts are not as good as you want.

 

As said before I own really a whole bunch of these XE's but I do not use them. Only for some testing.

 

Marius

[mimo]

It also states in B+Cs page that they have a different OS ROM, could that be the problem?

I have been thinking about buying one of these 130xs's as they look on paper to be fairly good value, but can the GTIA problem be fixed by swapping for a good GTIA chip and OS?

[Rybags]

I don't think the OS in use would make any difference.

 

Maybe the different OS ROM is the one which supposedly Self-Tests all 128K ?

[drac030]

There is some description of the problem here:

 

http://atariki.krap.pl/index.php/GTIA

 

This is in Polish, but as long as you can tolerate automated translation, you can take a look at this:

 

http://66.102.9.104/translate_c?hl=pl&...qvzvOvHxCVAN4Sg

[Rybags]

Defective layouts are those with a production date from 9040 to 9152 (the number placed on the right side of the symbol AMI).

 

If they're Year/Week numbers, then that could mean a fair number of machines.

[+Philsan]

drac030,

can you please attach or send me a non-arc version of your SysInfo 2.16?

[miker]

Here's zipped SysInfo ver. 2.16 (loose files).

si216.zip

[Marius]

About the OS. Not all these XE's have the 128KB selftest. Some have. And yes... that makes it not 100% compatible indeed. Swapping the GTIA and OS is the easiest fix to get the 'best' result. But My advice: also do some other graphic mods like Clear Pic.

 

Greetz

M.

[Mathy]

Hello guys

 

The schematics mentioned for the 1MB upgrade are mine. As you can see on the left, I live in the Netherlands, Europe.

 

Forget about Clear Pic. Look for the Super Video XE upgrade. It's much better.

 

If you buy a PAL machine, make sure you buy the right one. I guess most of western Europe needs the PAL B machines, the UK needs IIRC the PAL I machines. Difference is the frequency used for the audio. Look at the character written on the RF modulator of the PAL version you need.

 

There was a GTIA test utility that draws a couple of lines on your screen. Each line has a slightly different luminance/shade of green/grey (not sure, it's been a while). If your GTIA is good, you really see lines, if it isn't, some of the lines are rows of squares/balls (not unlike the ASCII character that's on the same key of your keyboard as this square bracket "]").

 

Greetings

 

Mathy

[mimo]

Hello guys

 

The schematics mentioned for the 1MB upgrade are mine. As you can see on the left, I live in the Netherlands, Europe.

 

Forget about Clear Pic. Look for the Super Video XE upgrade. It's much better.

 

If you buy a PAL machine, make sure you buy the right one. I guess most of western Europe needs the PAL B machines, the UK needs IIRC the PAL I machines. Difference is the frequency used for the audio. Look at the character written on the RF modulator of the PAL version you need.

 

There was a GTIA test utility that draws a couple of lines on your screen. Each line has a slightly different luminance/shade of green/grey (not sure, it's been a while). If your GTIA is good, you really see lines, if it isn't, some of the lines are rows of squares/balls (not unlike the ASCII character that's on the same key of your keyboard as this square bracket "]").

 

Greetings

 

Mathy

I believe that is true if you plan to use RF, but I have a Dutch 600XL (PAL B) and a German Jaguar (PAL B)that works fine on my Sony CRT (PAL I) with Component and s-video.

Edited September 9, 2008 by mimo

[Clint Thompson]

Old thread, I know - but does this mean my GTIA is bad on the 130XE I have? I can't see how or why it running through composite on an LCD would cause this? It looks like there are green broken lines...

 

[+Stephen]

That looks like the normal issue of the transition between luma 7 and 8, most likely being exaggerated by the LCD TV.

[Panther]

Yep, that's the way it looks on my LCD screens.

[+JAC!]

Check out the picture of the real bug und real machines here:

http://www.abbuc.de/community/forum/viewtopic.php?f=15&t=4275

[Bryan]

Old thread, I know - but does this mean my GTIA is bad on the 130XE I have? I can't see how or why it running through composite on an LCD would cause this? It looks like there are green broken lines...

 

image.jpg

I have a picture of what causes that here.

 

Basically, you're seeing the effect of the top bit coming in late on a 7->8 transition (0111->1000).

[monzamess]

Bringing this thread back. Just got a nice NTSC 130xe but its display has anomalies. I attached three pictures. First picture is result of running BASIC gradient program above. Second is another simpler gradient program, and third is the result of that program. Does this machine have the faulty GTIA?

 

 

 

 

[Rybags]

That's normal. Virtually any Atari with standard video circuit gets that annoying transition between certain luma values esp 7 and 8.

The problem is that since a resistor ladder is used to generate the voltage there's a little bit of lag with a result of the dropoff you see there.

 

The luma bar program could do with some modification - some horizontal bars as well might help:

 

 

10 GR. 9:D=1:FOR X=0 TO 79
20 COLOR C:C=C+D:IF C=15 OR C=0 THEN D=-D
30 PLOT X,0:DR. X,79:PLOT 0,90+X:DR. 79,90+X
40 NEXT X
50 G. 50

[monzamess]

Thanks! Right after I posted, I found your reply on this thread: http://atariage.com/forums/topic/233858-testing-gtia/. I meant to come back here and say as much, but I forgot. So is there a common video mod that would help?