MoBo on the Backplane

[hm_murdock]

I am, of course, talking about the Power Macintosh 6400/6500. The last Apple computer (and probably the last computer period) to ever use a backplane mainboard.

The board attatches to a forward bus slot upon which sits the ATA controller for the HD. The SCSI circuits are in the mainboard, however, but the connections are on the bus board.

3 PCI slots are provided by a riser board.

In addition to the 3 PCI slots, the 6400/6500 mobo has a Comm II Slot, one of the last times you'll ever see a custom bus slot on a computer. Comm II is made for modems and ethernet. Unfortunately, you can only have one or the other.

I'd like to get an ethernet card, but everybody's too cheap to make Mac drivers, especially for OS 9.

Oh, and of course, nobody has ever made Mac drivers even for old network cards. Why? Didn't need 'em! Power Macs have had ethernet built-in since the first PCI models, save for a few oddities, like the 5x00/6x00 series, which were consumer-aimed models.

Introduced in February of 1997, the Power Macintosh 6500 represents the last consumer-aimed Power Macintosh, and the last Apple consumer machine before the iMac.

[piratePenguin]

So stick Linux on it

[hm_murdock]

Yeah, great luck there.

OldWorld Macs require the use of BootX to run Linux, and it's a pain in the ass. It's a helluva lot easier and in the end, IMO, better just to run OS 8.6.

However, I do intend to give it a swing!

[obob]

Can someone show me a picture of what you mean by a backplane motherboard?

Do you mean a board like this:
http://www.technoland.com/backplane/tl-bp08s7p.jpg

and the CPU's either plug into it, or plug into riser boards into it (like older Compaq Proliants and some modern IA-64 systems)

Or do you mean something entirely different?

And I can't help you with the OS question, never messed with a Mac using anything but OS X...

[davidnix71]

Two weeks ago at work they threw away an external box that had a mac round serial connector on one end and rj-11 and rj-45 outputs on the box. Apple made it. It was probably in working condition, but I'm not interested in running OS 8 or 9 anymore, so I let it go.

NetBSD has quik which will boot directly into Linux and supports the 6400.

http://www.netbsd.org/Ports/macppc/

[hm_murdock]

obob...

The entire mainboard, including processor, plugs into an edge-connector slot on a combination power/wiring/speaker/port board.

On another riser slot that's on the mobo itself, are the PCI slots.

Pretty crrrazy design.

[obob]

wow, that's hard to invision, I don't see any advantages over something like ATX/BTX either, as having the PSU integrated into a mainboard provides for a more complex board + if it takes a surge other stuff is likely to go with it

[davidnix71]

There were DOS/Win processor cards. You could run more than one OS natively on the same machine. Upgrading was plug and play. Bus speeds were so slow it didn't matter that you were running from a pci slot.

[hm_murdock]

obob, the power supply is a standard ATX in the case. The difference is that instead of having a wire bundle and a connector, it's wired directly to the wiring board. There's a line of fuses to protect the mainboard.

As for upgrades, that's the main reason they went to this wierd design. The idea was that when the G3 procs arrived, there would be a mobo swap. That way, you have an entirely modernized board for your G3, and not just a proc upgrade.