Atari 600XL Memory Test shows BAD ROM

[atari_thomas]

Hello ...

 

I have a problem with my Atari 600XL. Last week, after years I took it out of the box and it still worked well.

I decided to upgrade the RAM from 16K to 64K. I found this tutorial http://atariage.com/forums/topic/183694-600xl-64k-upgrade-pictures/.

 

Now my machine has 64K of RAM and it works without any problem (apparently).

When I do the built in Memory Test (picture) it shows no error the first 1-4 runs, but then the left ROM bar turns red !

 

Well, the XL works fine so far. I can copy disks 1:1 (the copy prog. uses the whole 64K RAM), I can play games without any issue.

I can't find any error while working with the XL.

 

Has anybody an idea why the Memory Test shows up that red bar?

 

I already removed the ICs and cleaned their pins. Maybe the Atari has this issue because I'm running it without the metal shielding?

 

Thanks

 

[Caterpiggle]

Is your Atari 600XL has video port and PAL support instead of NTSC ?

[atari_thomas]

My Atari 600XL lives in Germany and has a PAL modulator plus a composite video port.

[Rybags]

No other upgrades? I had a problem with occasional graphics glitches because the AtariMax 32in1 OS I previously had in my 800XL upset reads on occasion.

 

Do you have another CPU and/or OS ROM you can swap in for testing?

 

My bet would be the ROM is probably OK, more likely some timing or other issue caused either by the CPU or memory selection logic.

[atari_thomas]

Is there a common ROM problem with the 600XL or 800XL?

I have some other XLs and some show up a problem with the RAM but I've never seen this ROM issue.

 

Unfortunately I didn't run the Self Test before I upgraded the RAM.

Well ... indeed it looks like I have to swap some ICs from my other 600XLs for testing.

[Rybags]

There's different revisions of the OS Rom among XLs - unsure if the SelfTest code is changed among them.

 

In my experience the 600XL usually has the one which immediately restarts the machine if a cart change is detected. The 800XL usually has the one which just locks up the machine then restarts when you press RESET. Although it seems not always the case, the 600XL I bought a little while back has the second one I described.

 

Testing another OS Rom though would be a good idea - unlikely you'd get 2 ROMs that failed in the same way, a failure with another ROM would tend to indicate the problem is occurring elsewhere.

[atari_thomas]

Where are these ROMs located in my picture (No.1-7) ?

[Rybags]

#7 is smaller 8K Rom (Basic) - doesn't get checked by Self Test so no need to do anything.

#6 is 16K OS Rom

#3 is 6502 CPU

[russg]

Hello ...

 

I have a problem with my Atari 600XL. Last week, after years I took it out of the box and it still worked well.

I decided to upgrade the RAM from 16K to 64K. I found this tutorial http://atariage.com/forums/topic/183694-600xl-64k-upgrade-pictures/.

 

Now my machine has 64K of RAM and it works without any problem (apparently).

When I do the built in Memory Test (picture) it shows no error the first 1-4 runs, but then the left ROM bar turns red !

 

Well, the XL works fine so far. I can copy disks 1:1 (the copy prog. uses the whole 64K RAM), I can play games without any issue.

I can't find any error while working with the XL.

 

Has anybody an idea why the Memory Test shows up that red bar?

 

I already removed the ICs and cleaned their pins. Maybe the Atari has this issue because I'm running it without the metal shielding?

You said the self test doesn't show the red ROM four times before it shows red. This is an intermittent then. Intermittents are really hard to trace down.

 

Thanks

 

1 GTIA

2. Antic

3. cpu

4 PIA

5 Pokey

6. OS ROM

7. BASIC ROM

 

No, running with shielding removed won't cause any problem.

 

If you can swap the OS ROM, that might help. Swapping the CPU might help, be sure not to short anything, don't set it on a screw or something.

Edited November 11, 2013 by russg

[atari_thomas]

Boooaahh ... I fixed it, finally.

 

I got a second (broken, shows no picture at all) 600XL, where I took the ICs from.

 

First I replaced the RAMs, then the OS-ROM, the BASIC-ROM, the Pokey, the PIA-Chip ... but always the same Red-Bar-ROM-Error while testing the XL.

Then I swapped the CPU ... and now the Memory Test works flawless for two days.

 

Really strange ... the 600XL actually worked fine, even with that (defective?) CPU, just only the Memory Test failed

[Rybags]

Possibly a marginal CPU with the Phi2 timing issue?

 

Sometimes the problem will be subtle like you seem to have but get much worse if PBI peripherals or internal upgrades are added to the machine.

[atari_thomas]

The printing on the Red-Bar-ROM-Error CPU says:

 

8323

co14806-03

c10794/322

Thailand

 

It looks like this is the original CPU of the Atari 600XL and nobody opened the case before.

[airsoftmodels]

I am so glad I found this thread. I recently purchased an Atari 600XL on ebay, and it arrived with the same ROM Test Error pictured above. This link was the first one I clicked on, because I know and respect the AtariAge site. With no previous experience fixing 8 bit computers, I confidently ordered the 6502 CPU and the 16K OS ROM. They arrived a few days later, I popped the old ones out and the new ones in, and everything works perfectly. Thank you Rybags and atari_thomas for this topic, and thanks to B&C Computer Visions for having the parts at an affordable price. By the way, I have since become a member of atariage, I think this is my third post.