SE vs. Portable ROM, 8 MB RAM in SE?

[trag]

This tech note:

http://developer.apple.com/legacy/mac/library/technotes/hw/hw_13.html

states that:

"The Macintosh Portable contains 256K of processor ROM, which is fundamentally

the same as the ROM in the Macintosh SE."

I wonder how similar "fundamentally the same" is?

Does that mean that if you put the Portable ROM in an SE and adjusted some decoding in the GLUE chips to point at the right places the SE could have 8 MB of RAM? I guess you'd also have to rebuild the RAM controller. Oh well. Sigh.

Now I kind of wish I'd picked up one of the old Portables at Goodwill back when they had them for under $30...

 

[Trash80toHP_Mini]

That's an interesting notion, but I kind doubt its application in the "real world," but I've been wrong before. If you want to address more RAM in the SE, watch eBay for one of the old Gemini Accelerators, IIRC, they could address up to 32 MB of Ram on the SE. They needed to address 28 MB as Virtual memory, but it operated at silicon speed, not HDD access speed.

IF the Luggable's ROM will work in the SE, there's something more interesting that you can do with it. I was looking over some of the Portable ROM Slot Specs in GttMFH: Second Edition and found out that the Portable can access its onboard ROM IN ADDITION TO another 8 MB of ROM on the expansion card in Burst Mode, just like it addresses its RAM!

I was thinking about those oldtime Gemini Cards and their VM Scheme/HackAround for the SE and began wondering about putting it into action. Laying out a Portable ROM Card to access 8 MB of SRAM as VM would be duck soup!

< tangent mode >

I know it can be done because I came up with the same scheme to address SRAM as if it were ROM as a "Font Emulator System" for my Sign Making Machine back in the day! My programmer/hardware partner gave me the specs and I did the PCB layout/prototyping and he soldered it all together. We demo'd the prototype for another friend of mine and he bought in, right on the spot, as a minor partner. That financed a short production run and we sold a bunch of the units! [] ]'>

Didn't make any money, but I got a LOT of experience, some travel opportunities, AND a bunch of really great toys out of the deal. [] ]'>

< /tangent mode >

Whatever, if we can get a RAM-Disk+ or VM kinda program going here in the 68kMLA, I'm sure we could have some real fun with the Compacts . . .

. . . AND the Portable! }

 

[H3NRY]

Does that mean that if you put the Portable ROM in an SE and adjusted some decoding in the GLUE chips to point at the right places the SE could have 8 MB of RAM? I guess you'd also have to rebuild the RAM controller. Oh well. Sigh.
Now I kind of wish I'd picked up one of the old Portables at Goodwill back when they had them for under $30...

You *could*, but... You could move the ROM addresses to $90 0000 in any compact Mac by fooling with the address decoder PALs, so they could have 9 MB of RAM like a Portable (8 MB in a 5126). You'd have to go thru the ROM and correct every place where non-relocatable code exists. The hardware is different enough that the Portable ROM wouldn't correctly initialize an SE, but the toolbox and OS parts are the same. So yes, it's theoretically doable. In practice, I doubt it gets attempted.

I did pick up a couple of those Portables. Want one? PM me.