How do I know if my macintosh II has a PMMU or HMMU?

[NegativeLatency]

Background: I have a macintosh II that I'd like to get A/UX running on (it's partially complete, needs a hard drive and a video card)

I'm not sure if the main board has a PMMU or HMMU (I suspect it has an HMMU and was wondering if anyone knew for sure)

Here's a shot of the CPU, FPU and the MMU which doesn't appear to be the MC68851 chip.



Follow up question, could I replace the existing MMU with a PMMU like the one on this ebay listing: https://www.ebay.com/p/556755362

 

[NegativeLatency]

I think I found the answer in "Macintosh II Repair and Upgrade Secrets", my board has the HMMU

Seems like that part from ebay will work?

 

[360alaska]

Yep, PMMU usually has a gold top.

 

[NegativeLatency]

Also found this on the AppleWiki 

The 68851 allows a 68020 processor to support virtual memory. The only Macintosh model with a socket to accept a 68851 was the 68020-based Macintosh II. However, the socket was shipped with a lower-cost VLSI VI475custom hardware memory management unit (HMMU) which did not support virtual memory like the more expensive 68851.

https://apple.fandom.com/wiki/Motorola_68851