Sanyi

Hello, CPU arrived and replaced all is working fine! Once I'm inside, I made the memory expansion also. A happy 600XL (with 64kB RAM) owner, that's what I am!

It was the CPU. A generous 600XL owner I know lent me his whole computer. I switched the CPUs first: the infinite loop runs until BREAK is pressed, memory-test remains green. In his machine the loop stops with error..

Mmmkey... Checked the soldering, of the ROM sockets and they seems ok. Both of ROM chips were removed and I've checked their contents. BASIC is revC (8kB), OS is REV-02 (16kB). Checked several times with my eprom burner (TL866CS) and they contained what they should. (ROM images are from here http://atari.vjetnam.cz/index.php?frame=roms, I guess they are OK). For being sure, I took out the CPU and re-seated it. Checked the continuity in the socket (seated ROM pin with CPU pin), all seemed fine. Started my 600XL, no change. 10 goto 10 fails this time with error 12.. Started up a memory test and on the third round the first ROM bar turned to red... Which one is the first ROM? In the service field manual I just read that the memory test should not be running more than 7 minutes, because of high risk of the image burning into my monitor, but it is not written, which bar is which ROM (and both of them described as 8kB ROMs).. I dared to left the test running - I live my life dangerous and don't care about burnt monitor displays - while I was typing this reply. Both of the ROM bars became red. WTF? I think the RAMs are fine, at least they are green, DelayLine (RAS, CAS) should be OK. I wrote two 28C256's and executed the test again.. Well, when the OS was replaced with a 28C256 (2x 16kB, rev-02), the 600XL didn't boot. When only the BASIC was replaced with a 28C256, the machine booted, but with the same symptoms. After a few minutes of memory test left ROM bar turn to red, simple basic infinite loop stops with an error after 1-2 secs. (images were taken with original chips) Next steps: - I will replace the RAMs with 4464's (41464) - new sockets for the ROMs and try to pursue my a fellow 600XL owner to lend me some of his ROM chips to test.

I spent some time carefully inspecting the pictures in the post you sent and also the schematics of the 600XL and now I hope I understand what was the original purpose of the creator of this 24-28 pin layout. Actually this is not that uncommon, I've seen this kind of trick in the Plus/4 MoBo also, but there it is specifically stated that 2364 <-> 23128 was the aim. Thanks a lot for all the hints and tips for all of you!

By the way. Is it normal to have all the chips socketed on a 600XL motherboard? On the other hand I guess it was not common to replace the BASIC ROM with a custom 2764 this way? Unfortunately I don't have picture on the other side but it seemed to me normal PCB seat. From the solder side. No hacking, no patchwire..

I will try to reseat the chips. This is my latest test program... Now the 600XL doesn't hang (neither starts the built-in test...), just stopped with error, after 1-2 secs of running. What is error code 11? Where can I find the error codes defined?

Almost the same as above: 10 PRINT "SANYI RULEZ" 20 GOTO 10

Hello Mike, What was the conclusion with your machine? I have bought recently a 600XL with the same symptoms: machine seems working, tests passes, but the two-liner basic program crashes after a few seconds of running. All chips are socketed inside, and it has a 2764 chip on the top right corner. I know PAL machines are different compared to NTSC but not that much, right?