Atari Mega ST4 Rev 5.0 Question

[jhuyett]

Hello All,
Taking apart an Atari Mega ST4 for cleaning and found a modification on what I believe is the CPU.
I'm able to find other pictures of this when searching for the number on the board: CIO3261, but curious as to what this does/ whether it's a feature of this specific board revision.

Thanks for reading and any info.

Regards

 

[Timo W.]

That's Atari's kludge to make the blitter work.

 

[jhuyett]

Thanks for the response. I had read something on the blitter, but didn't connect the two. Thanks for the info.