Atari 400 with weird issue.

[+Allan]

I have a 400 that has a weird issue. I can play over a dozen cart games with no problem. I have tried other carts like Microsoft Basic that seem to work fine but the three different carts of Atari Basic crash. The 400 has 16K. When I boot the computer you see the blue and then the "Ready" message comes up. But after that it freezes. I can't type anything. Even system reset doesn't work. I can type in Microsoft Basic cartridge with no problem. Some time with Atari Basic an inverse K shows up in the middle-ish of the screen but that's it. Any thoughts?

 

Allan

 

[Paul Westphal]

Take it apart and clean everything; contacts on the ram and hidden card, reseat all chips. Go from there. Bert electronics has super salt diagnostic carts for $25 I believe. Also skinny up a qtip and clean cart port with rubbing alcohol.

Edited September 2, 2017 by Paul Westphal

[Paul Westphal]

It's probably the lower part of that ram card.

[+Allan]

Thanks Paul.

 

I got this issue before I opened up the 400. I added the new 400 ram upgrade card from tf_hh. Same issue. I tried Microsoft Basic cart and it's telling me I have the same ram now as my 800XL does with the same cart. I tried reseating all the socketed chips with the same results. Maybe I'll have to try to get a copy of the test cart to see if that catches anything.

 

Allan

[BillC]

Take it apart and clean everything; contacts on the ram and hidden card, reseat all chips. Go from there. Bert electronics has super salt diagnostic carts for $25 I believe. Also skinny up a qtip and clean cart port with rubbing alcohol.

Rubbing alcohol is only about 70% isopopyl alcohol, with oil and other additives, recommendation is to use 95%+ isopropyl alcohol.

 

In Canada 99% isopropyl alcohol is available from many pharmacies, I don't know about availability in other countries.

[Kyle22]

Gasoline anti-water/ anti-freeze commonly known as "Dry Gas" is as close to pure alcohol as you can get for the price. Just be aware that it comes as isopropyl or methyl alcohol. The isopropyl is better.

[+tf_hh]

I have a 400 that has a weird issue. I can play over a dozen cart games with no problem. I have tried other carts like Microsoft Basic that seem to work fine but the three different carts of Atari Basic crash. The 400 has 16K. When I boot the computer you see the blue and then the "Ready" message comes up. But after that it freezes. I can't type anything. Even system reset doesn't work. I can type in Microsoft Basic cartridge with no problem. Some time with Atari Basic an inverse K shows up in the middle-ish of the screen but that's it. Any thoughts?

 

Allan, did you try to use the O.S. usage from my RAM card instead of using the ones on the mainboard?

 

This behaviour sounds like a defect math-ROM. The mathpack routines are not used by the O.S. itself and also not by most standard programs. Atari-BASIC need the mathpack and will exactly handle this way if mathpack is missing or defect. So try using the O.S: (including mathpack) from the new RAM card... maybe then Basic works fine.

 

Jurgen

[+Allan]

Thanks Jurgen,

That did it. BASIC seems to work fine now.

 

Thanks,

Allan

[+tf_hh]

That did it. BASIC seems to work fine now.

 

Cool! It´s something strange... this is the sixth or seventh time I had myself or hear about a defect math rom on an 400 mainboard or at a 800 personality card. Seems to be an aging problem with these mask roms. I bought several years ago 6 pieces from BEST, all of them are used for exchange until today.

 

So the "addon" feature (external ROM) saves money twice

[+Allan]

That's good to know and document here so people who have the same issue.

 

Allan