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R.Cade

130xe Troubleshooting

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Posted (edited)

Hello friends,

 

I received a couple of 130xe's in a trade recently. The first one I was able to find 3 bad RAM chips through piggybacking, so it is back up and running.


The second one has these symptoms:

The screen comes up with random flashing/rapidly changing things on the screen.

The computer is "running blind" meaning it loads from disk, runs programs, I can hear the sound and type. 

The things on the screen do change based on what the computer is running. Mostly color changes I can tell... (blue BASIC screen, etc.)

It's not bad RAM. I have swapped the banks and no change in behavior, and again the machine runs blind.


Is this more likely the ANTIC or GTIA?  Neither are socketed, and I may just go ahead and socket both while I am in there. Just trying to get an idea which it might be.

 

Edited by R.Cade

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among other things, ANTIC controls the character set and player missile graphics. these are fed to the GTIA for video output.

the GTIA could be fine, it may just be being fed corrupt data if the ANTIC is amiss.

it happened to me on an 800XL. the display and text were unstable but the computer still worked. the only way is to try the suspect chip in a known working atari and see if the issue moves over with it. but the downside is XE chips are not socketed and you have to be uber-careful when desoldering anything from an XE board because they were built down to a (cost-saving) price...

hope this helps

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Just now, flashjazzcat said:

It doesn't matter which chip you socket first: it'll be the other one. :)

That is absolutely true. :)

 

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Do you detect any tearing or rolling in the display. If not, your are on the correct track in suspecting our dynamic duo. GTIA and ANTIC. As FJC said... it'll be the other one :)

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Posted (edited)

I would say the distortion looks kind of like tearing or rolling at times, but it's not a loss of sync on the monitor...


I'll make a video of it this evening for the curious. :)

 

Edited by R.Cade

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It could be the non inverting buffer ( cd4050 ) after the GTIA at the output.

 

I had something similar to what you've described.

 

unnamed-7.jpg

 

 

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Posted (edited)

Somehow I beat the odds. I socketed the ANTIC first, and replacing that solved it.

:)

 

Anyone have a spare to sell?  NTSC C021697 (-31 was in it, my 600XL temporary transplant donor has -11)

 

I see someone is selling ANTIC out of 5200's on eBay, but it is a different part number.

They are selling C012296D... I assume that will not work?

 

Edited by R.Cade

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55 minutes ago, R.Cade said:

Somehow I beat the odds. I socketed the ANTIC first, and replacing that solved it.

:)

 

Anyone have a spare to sell?  NTSC C021697 (-31 was in it, my 600XL temporary transplant donor has -11)

 

I see someone is selling ANTIC out of 5200's on eBay, but it is a different part number.

They are selling C012296D... I assume that will not work?

You can buy replacements at BEST can't you? 

 

I know the later ANTICs have a different part number but I can never recall what the changes were or how they matter (if at all).

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C012296 has 7 bit refresh while

 

C021697 has 8 bit refresh due to being a later version for XE use with the extended memory fad.

 

Only becomes an issue if you are going to need the later and better 8 bit refresh for massive memory upgrades.

Otherwise they should work.

 

Me neither, had to wiki it since I also couldn't find my rambo schematic which has an added IC to supply the missing bit of refresh if you happen to have the early ANTIC. I can't find it - it's always in the way any other day...

 

And wiki doesn't cover the refresh difference either...

 

The dash 13 part is a date code or other superfluous information that needs no attention paid to it all. It becomes important in eprom work, but this isn't that.

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Posted (edited)

Thanks - I will order the older one since they are on eBay for $4 at the moment. Hopefully that will work in the 600XL (with just the 64k upgrade) and I'll leave the newer one in the 130xe.

 

I'm glad I didn't try the ANTIC from my 400, as that probably wouldn't have worked and caused me to socket the GTIA, which also would not have fixed it, and I would have been stuck. :)

 

 

EDIT: Bah, the 4464 needs 8-bit refresh, so that will not work. Oh well...

 

Edited by R.Cade

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Posted (edited)

OK, now I found a conflict. The original "Atari 8-Bit FAQ" conflicts with the 7b/8b refresh story.

 

http://www.atari800xl.eu/faq/atari-8bit-faq-us-letter-format.pdf

 

"The ANTIC chip also generates DMA addresses for the (entirely automatic) refresh of on-board dynamic memory RAM (DRAM). ANTIC versions C012296/ C014887 use an 8 bit refresh cycle counter, supporting DRAM chips including those requiring 128 cycle/2ms or 256 cycle/4ms refresh (standard 16KiB and 64KiB DRAM chips). The C021697/C021698 ANTIC versions use a 9 bit refresh cycle counter, supporting additional DRAM chips that require more refresh cycles (standard 256KiB DRAM chips)."

 

However, later in the exact same document:

"FREDDIE -- 800XL("800XLF" and SECAM),XE(all):C061922/C061991 ======= According to Atari's design specification (C061922), the "Freddie RAM" Memory Control Unit (MCU) is a custom LSI chip providing dynamic RAM (DRAM) control functions. It replaces a number of small-scale integration (SSI) and mediumscale integration (MSI) transistor-transistor logic (TTL) parts, including a custom delay line. FREDDIE multiplexes 16-bit RAM addresses from the processor bus into 8-bit row and 8-bit column addresses for direct use in the DRAM, and it generates row and column DRAM address timing strobes. Any functional difference between the C061922 and C061991 FREDDIE versions is not well established. It is theorized that the original C061922 was designed to work with the earlier C012296/C014887 ANTIC versions with 7 bit DRAM refresh address counter for 128 row addresses, while the later C061991 also supports an 8 bit counter for 256 row addresses as generated by the later Atari 8 bit computers. Both versions carry the 1983 copyright date."

 

So which is the real story? Or am I misunderstanding...

Edited by R.Cade

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C021697  C021698? Because that's what I've use on the XL XE series forever, no problems with any memory configuration.

the older choices? not so much.

 

You will find plenty of discussion about this here on AA. No need to rehash it. The available refresh is what is needed, and gets the job done.

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The one from the 400 would have worked fine.

 

It's only the bigger memory expansions that needed the 8 bit refresh anyway. Atari saw a problem ahead and fixed it well before they ever needed to when they issued the 8 bit refresh ANTIC. Early XE is only using twice the bog standard 64k and their switching method between the two banks of memory doesn't require anything so special as 8 bit refresh. It's the 64k x 4 chips that sometimes need it depending on internal arrangements. Atari only used those at the very bitter end.

 

It was never 8 VS 9 bit refresh, they have the numbers confused with 7 VS 8.

 

ClausB is our very own resident ram guru.

https://atariage.com/forums/topic/176772-how-to-fix-refresh-problems-dram/?do=findComment&comment=2208939

 

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Posted (edited)

Please go with what was suggested, later in the thread he noted you will read...

quote

That's probably more complicated than the CAS-before-RAS circuit. In my 256K upgrade for the 800XL, I used an 8-bit counter to add an 8th refresh bit to ANTICs with only 7 bits.

unquote

it is a 7 bit available refresh antic vs an 8 bit available refresh antic.. make your life easier... just go with the readily available 8 bit antic... should you decide to add something later, whatever it may be you won't be building counter circuits etc or replacing it again...

 

It is understandable to want to save a dollar, in this instance I'd spend the dollar. Easy now and possibly easier later.

Edited by _The Doctor__
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If you already had the older ANTIC on hand, I'd say try it. Since you
have to buy one, might as well buy the newer one.

...at what point do we start pronouncing ANTIC as "antique"?

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As many have already stated, stick with the C021697 ANTIC.  I tried to replace RAM in a 1200XL with 256 refresh and it wouldn't work with the old ANTIC.  So if the 130XE has RAM that requires 256 refresh, the older one might not work.

 

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6 hours ago, ACML said:

As many have already stated, stick with the C021697 ANTIC.  I tried to replace RAM in a 1200XL with 256 refresh and it wouldn't work with the old ANTIC.  So if the 130XE has RAM that requires 256 refresh, the older one might not work.

 

Conversely, all 3 of my 1200XL’s have original-version ANTICs and worn fine. A modern expansion like an Ultimate 1MB board doesn’t require the newer revision chip. 

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I tend to dislike following along with the modern day tendency of using the exceptions as the rule and re-branding the rule as if it was the exception. It leads to a dark path in electronics as well as the general discourse we all experience these days.

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Posted (edited)

More questions than answers...

 

I got in the ANTIC C012296D pulled from a 5200.


It works fine in the 130xe *and* it works fine in the 600XL that has 4464 RAM in it (upgraded to 64k).

 

The spec sheet for the 4464 RAMs says it needs 8-bit refresh. If this ANTIC only provides 7, how is it working? Perhaps the original part of the FAQ is true and the original ANTIC is 8-bit, and the newer one is 9-bit?

 

Edited by R.Cade

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good job on the repair - another one resurrected! :)

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20 hours ago, R.Cade said:

 Perhaps the original part of the FAQ is true and the original ANTIC is 8-bit, and the newer one is 9-bit?

 

NEVER.

The 64 x 4 memory are famous for holding onto memory many seconds after power down, this is due to the much better silicon being used by the time they came along. It's "working" only because of that trait and not the 7 bits of refresh it's getting from the older ANTIC. All 4 bit wide memory is like this, only the one bit wide memory will forget its contents in the time it takes to shut off the computer and turn it back on.

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