Announcement concerning the Genesi/Phoenix collaboration

[downix]

That's possible. Unless they have someway to emulate AGP on the PCI bus? The AGP signal set is a subset of the PCI Bus. After a discussion I had with a chap on the AmigaOne mailing list, it seems the internals of an AGP device have additional registers (GART) and they lack a few features of PCI.

Most of the difference between AGP and PCI is inside the chip, not in the bus itself.  There are several techniques to bridge an AGP bus onto a PCI bus out there.  I would point out that the Marvell has PCI-X, which rivals AGP 8x in speed.  This means that some bandwidth can be lost in the translation process and still get top-speed AGP functionality.  Even a standard PCI 64-bot 66-Mhz bus can be bridged to deliver AGP 2x speed to a peripheral card.  The card doesn't *care* how the northbridge actually handles it, so long as it gets the bandwidth needed.

I would note, Genesi has several talented VHDL/Verilog coders among their staff.

[downix]

of course the card doesn't care, but what I don't understand why it is cheaper or more effective to build this bridge solution than to just build a northbridge that does what you want.

The logic needed is far cheaper.  An AGP bridge to PCI uses between 2000 and 3000 gates, that's a $2 programmable array.  A whole northbridge can run upwards of 400,000 gates for a simple one, over a million for one that can match the Marvell in performance.  A 1 million gate array that runs at the speed needed is $300 or more.

As for the final speed, the speed won't go down any from the bridge, but nobody will commit to the final speed until we've finished testing it.  Genesi does not like to break promices, and while we are very sure that we can get one speed out, we're making damned well sure first before advertising it.

[downix]

Yeah, but how many PCI-X graphics cards do you see available on the market???

A few, but why do you ask as there won't be a PCI-X slot on the motherboard, just the PCI's and an AGP slot.

[downix]

So you would be limited to AGP2x speed even with an AGP8x device ...

Untrue, AGP 8x devices *cannot* run at AGP 2x or lower speed.  Only AGP 4x and 8x is possible with those cards.