What Chip is this?

"I didn't find what , exactly, this IC is but here is an interesting site that lists many of the IC's used in Apple computers. The closest match is the 344S0607-A and it dates back to the Apple IIc.

VLSI, the manufacturer, did custom ASICS so as such this is not a CPU but an application specific IC. Hopefully, @mayer will have more info."

This is the BBU - essentially the main ‘chipset’ of the mac that handles generation of /BERR and selection of custom IC’s based on interrupts.

This is the BBU, or the Bob Bailey Unit. See The 8-Bit Guy’s video on the Macintosh SE for more info.