Mac II PowerCache Adapter - divining its unique secrets . . . maybe.

[Bolle]

Started working on the Mac II adapter here: 

 

[herpderp]

Awesome!!  I'll have a look at that thread.

 

[Trash80toHP_Mini]

The diagram is labeled wrong, that's a MC68851 not a 68881.

Yep, noticed that and made note of it above, but got sidetracked by something else and never completed/updated the pinout graphic.

The chip is a PMMU and basically maps logical memory address to physical ones (LA = logical address, PA = physical address, etc)  FC is function code, iirc.

What I find most interesting about that adapter is the flow of the traces Bolle pointed out. They pass through the socket pins, but the PMMU was an option, everything works fine sans PMMU in a stock Macintosh II.

One of the first books I picked up as a young nerd was my dad's MC68020 programmer's manual.  I think it's still kicking around somewhere, along with the MC68851.  Let me know, I can dig all this up.  I miss this stuff

Cool, my dad was a boffin at IBM's Glendale Labs, so I grew up studying the masks for complex ICs in the VLSI textbooks because they were such beautiful artwork. So I see things a bit differently and miss hanging with my dad while he was doing technical stuff. Welcome aboard, it's great to have another hardware/software nerd from the day involved in Hacks and Development. There are a few of you guys kicking around.

 

[Bolle]

but the PMMU was an option, everything works fine sans PMMU in a stock Macintosh II.

But you would have the HMMU in place then if you didn’t opt for the full PMMU.

Without anything in the MMU socket the II will not work.

 

[herpderp]

Yeah, we're still kickin around, here and there.    I regret not keeping a lot of my old Mac stuff (II, IIsi, IIfx, quadra 700, 840AV, etc).  Sigh.  I should start collecting again.  I still have a bunch of of old MAcWorld demo disks and MacOS CD's and such.

 

[Trash80toHP_Mini]

But you would have the HMMU in place then if you didn’t opt for the full PMMU.

Without anything in the MMU socket the II will not work.

AHA! Live and learn, thanks.

Yeah, we're still kickin around, here and there.    I regret not keeping a lot of my old Mac stuff (II, IIsi, IIfx, quadra 700, 840AV, etc).  Sigh.  I should start collecting again.  I still have a bunch of of old MAcWorld demo disks and MacOS CD's and such.

I lost most of my stuff down a storage room whirlpool while I was hospitalized. Luckily most of the best was in my apartment. Once in a while I really miss something, but not all that often and I have no intention of hoarding that much stuff again. :blink:

 

[Paralel]

AHA! Live and learn, thanks.

I lost most of my stuff down a storage room whirlpool while I was hospitalized. Luckily most of the best was in my apartment. Once in a while I really miss something, but not all that often and I have no intention of hoarding that much stuff again. :blink:

Ugh storage room losses are the worst. There should be some legal protection regarding hospitalization. I had something similar happen to me when I was in the hospital for awhile.

 

[techknight]

Thats why I dont use storage. If I have to get a storage unit, that means I have too much and need to get rid of.