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BlackMagicalBus™ for Memory/PDS Subassembly of reduced footprint LCIII in Classic Project, etc.
Posted by: Trash80toHP_Mini on 2022-03-22 16:23:34
Roots or this craziness to be found in the MagicalBus™ thread for the budding LCIII in SE project. PDS dungeon breakout required fot that one, but it's only a one way street. Inspiration for that was Radius' fabulous Magic Bus implemented as an adapter card for what was built into their SE Accelerators.

LCIII in Classic poses a brand new problem so I've moved on from PCI Connector to the much tighter pitch, 240 pin DDR2 Memory Module as the LCIII Memory/PDS Subsystem interface which will be running 120 connections up one side of a tall format take on the DDR2 DIMM and back down the other 120 teeth on the edgecard connector..

Was figuring that a notch on one side and a bit of an arc on the other and angled insertion and removal would work:

1647990279297.jpeg

But KISS principle violation forced me to break out of the Symmetry/Parallelism box constraint. Once outside the box, it pretty much fell into place.

BlackMagicalBus-Concept-00.JPG

BlackMagicalBus-Concept-01.JPG

Once upon a time, by doing the same thing I came up with the suggestion for fitting something similar on a 10cm Square PCB. 😉

Note the band of Surface Mount Memory on the board as above, the Unit will look much like this 72pin SIMM expander:

Classic_III_Memory_Riser-01.JPG

Surface mount pad real state available for banks of memory on both sides of the riser available under SIMM, VRAM and ROM connectors, per
@max1zzz suggestion.

At any rate, @k24a1 suggested a Compact III project, and here a bit of it lands with a thump.

Idea: Macintosh Classic III (LC550+M1420)

I have a Macintosh Performa 550 motherboard sitting around, probably hasn't been turned on since 2004 according to the person who gave it to me. I also have a Macintosh Classic (M1420 RevB) which is probably one of my least favorite compact macs because of how it was released at the wrong...
68kmla.org 68kmla.org
Posted by: Trash80toHP_Mini on 2022-03-22 16:32:08
Part II: post was too long, too many pics it would seem: diagrams

DDR2-BlackMagilBus-PCB _Egecard_Spec.JPG

DDR2-BlackMagilBus-Connector_Spec.JPG

Dimm Slot is a much more rigid interface than the MagicalBus PCI /slot/Card proposed in the earlier thread and locked in as well. On the forward side the extractor should be fine I think, but the ear of the backside extractor latch may need to be filed down a bit, if overhead is too limited, but would still remain fully functional I think.

Well there it is @max1zzz whatcha thinking?
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