Mystic PPC WITH Apple IIe card

[nottomhanks]

Hello all! I was reading on This Old Mac that the Apple Power Macintosh Upgrade Card for the 575 precludes one from using the LC PDS slot.

BUT….

I thought, what if you used a PDS extension to “raise it up” overtop of the Power Mac card? Would the IIe card be recognized? Would it work?

The answer is YES!!

I’ll be editing a video that documents this, but I was running Total Replay with 7.5.5 with this setup!

Just need to install the Power Macintosh Card control panel, and might need to look at additional cooling, as I have @Kay K.M.Mods Spicy O Clock running at 44Mhz with the help of @JDW suggestion of using OS-CON caps, and I’m also running Mr. Fahrenheit’s VRAM.

Super exciting!!

 

[JDW]

Holy cow! That’s amazing. Thanks for sharing.

 

[ClassicHasClass]

Nice work, though I'm assuming that means it works with the PowerPC card deactivated.

 

[JDW]

I myself don't have one of those PPC cards, but I'm curious if they have an 040 mode. What I do know is the IIe Card requires 24-bit addressing. Normally, you would be using 32-bit addressing to access all of your RAM. That limitation also means that you cannot use System 7.6 or newer as those operating systems force 32-bit addressing to be on all the time.

 

[nottomhanks]

Yes, that card allows you to boot into 601 mode OR 040 mode. I’m guessing the PPC card will NOT run the IIe card if it requires 32 bit addressing turned on. I actually haven’t installed the Power Macintosh Card control panel yet, so I haven’t actually booted into PPC.

 

[nottomhanks]

Also, apparently because of the 601 rom limitations, it doesn’t see all of your installed RAM, which is crummy. The 040 recognizes the full 128 Mb, but it takes a while to count it when cold booting.

 

[JDW]

@nottomhanks
I am able to boot my PowerMac 9600 into System 7.5.5 even though it has a Buffalo 400MHz G4 (7400) CPU card installed in place of the stock 300MHz 603e CPU card from Apple. So unless your PPC card requires 7.6.x and higher, you should be able to boot into 7.5.5, disable 32-bit addressing and find the IIe Card still works. That is in theory though because no one has yet tested your config. You're breaking new ground!

How much RAM can the PPC card see? 36MB?

 

[nottomhanks]

I believe 36 is max, 32 from the SIMM and 4 from the logic board.

 

[nottomhanks]

 

[JDW]

Because of the System 7.5 requirement, I assume you are no longer able to boot into System 7.1 even when you switch over to the 68040 CPU?

 

[nottomhanks]

No, I’m still able to boot into 7.1 with the 040.