*snicker* Ironically if you look all the way back to how the SCSI port is implemented on the Mac Plus you'll see that the Q630's IDE interface is pretty much par for the course. I still get a little amused when reading old pro-Mac polemics ragging on aspects of PC clone hardware that are ugly kludges. If you're comparing pre-1998-ish hardware it's a *serious* case of the pot calling the kettle black. ;^)

Anyway, I have to admit I'm a little confused by some of the technicalities of what you're asking for... which seems to be a magic disk interface that offloads file system operations in such a way that a Nubus video capture device can stream data straight to it rather than depending on the host CPU to moderate. Were there SCSI/Nubus video board set combinations that actually did that on the Mac platform? With the classic Mac's weak/nonexistent support for DMA and busmastering it seems to me that such a combination would require some pretty specific things be embedded into the CPUs on the capture and SCSI card respectively. If you can point to a combination that actually did that as opposed to a SCSI controller that merely provided a faster interface than the built-in one (and perhaps some onboard caching) but was otherwise treated the same way there might be a point of reference to work from.