Atari 520 ST (8/1985) S/N C070115 REV.2B motherboard ?

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Atari 520 ST (8/1985) S/N C070115 REV.2B motherboard ?

Postby ZeroG1972 » Fri Aug 31, 2018 7:31 pm

Good evening,

I bought on eBay a 520 ST from August 1985 (separate power supply and floppy disk drive). I can not get a readable display on my color screen (this is not a screen issue, it works well with a 520 STE). I wanted to disassemble it for but I was blocked by the armor plate that was welded on each side. After un-bidding, I was able to access the motherboard.
I was surprised that the version of the motherboard seemed earlier than I could find on the Web: C070115 REV.2B
At the first Atari 520/260 ST have a higher version number: C070243

I have many qustions :
Is there a complete list of Atari ST motherboard versions?
What is this version number, how to decrypt it?

For information, it is AZERTY (French) keyboard. The serial number below the box is : A1 1007193 8 1985
I enclose some photos, thank you in advance for your answers :

Thierry (from France)

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Re: Atari 520 ST (8/1985) S/N C070115 REV.2B motherboard ?

Postby czietz » Fri Aug 31, 2018 9:09 pm

The wiki has a long list of revisions, including a C070115 Rev. 2, which is probably still a bit earlier because it has -20 (Universal Semiconductor) ASICs, while your mainboard already has -38 (Ricoh) ASICs. ... _revisions

Still, yours is an early model indeed. I see that it only has boot ROMs and will have to load TOS from floppy.

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