Atari 800 memory error? Please help.

[TapperP]

I bought an Atari 800 with 48K and a 1050 drive last week from a forum member. It is very nice and clean, but I'm noticing it will crash after a little while. For example I ran Joust (from disk) and let it run its demonstration, and after about 10 - 15 minutes the game will start corrupting onscreen, then just crash to blue screen. I re-seated the RAM and OS modules under the hood, but that has not fixed it.

 

From my initial tests, it seems cartridge games don't crash, but games loaded from disks do. This made me think I may have a bad RAM board.

 

I found a RAM test program (https://www.atariarchives.org/c2ba/page015.php) and am using that now to test RAM. It's very, very slow though.

 

The memory test program is finding errors, but they always say the same thing: "ERROR at 37120 EXP = 106 ACT = 106"

 

I'm not completely sure how this test program works, but it is now around 400 passes. I have gotten that same error 4 times so far.

 

Can someone help interpret these results and figure out which RAM module(s) may need to be replaced?

 

PHOTOS: the first one is the first time I got the error, the second is the 6th time. I'm not sure when this program will be done, but it has been running for hours now...

 

Edited June 14, 2020 by TapperP

[_The Doctor__]

something does not make sense... you need to double check your program...

 

have you moved the modules around. if you test it cold versus hot... is there a change?

 

rotate the memory carts, if the error moves then you have part of the answer,

then check them one at a time by placing them in one at a time in the first slot.

if they all have errors I'd suspect another issue

if only one memory card shows an error you can fix the card or replace it.

 

if they all check out great

 

make sure the programs you are running are not full 64k programs. 52k is the limit with most standard 800 memory configs, but there are nice upgrades out there taking the 800 much higher and handling the XL/XE os and their memory schemes as well.

 

I'd grab some other memory testers and run them as well.

Edited June 14, 2020 by _The Doctor__

[TGB1718]

If the test is accurate it would indicate that the RAM in the second slot is the faulty one.

 

As for the error message, my guess is that it's not reporting correctly

 

try finding onother RAM tester

 

Just remembered I wrote a RAM tester some time ago, but unfortunately currently

it only tests Banked RAM and the 16K under the OS in 130XE's

 

 

Edited June 14, 2020 by TGB1718
Update

[ClausB]

Assuming the program is correct, 37120 is above 32K, so it's in the third 16K board. To verify, swap the second and third boards and see whether the error address goes below 32K.

[+toddtmw]

You could also remove one at a time until the problem goes away to tell which is the bad one. (You’d need to use a game that fits in 32k of ram...)