Subject: Re: Oooooh... IDE to Q-bus/Unibus adapters.
To: Allison J Parent <>
From: Michael Kukat <>
List: port-vax
Date: 07/07/1999 18:00:52
Hi !

> <huh? i'd tend to disagree!! IDE forces the host to perform all the work! 
> And PIO SCSI doesn't???
> Both can run with DMA, and unless your running wide scsi or ultrascsi
> most IDE drives can be IO'd pretty fast!  Keep in mind that IDE the 
> DATA path is naturally 16bits wide and the commands/status do not share 
> the same address.

Don't compare modern IDE drives with old SCSI-II drives. SCSI can do lots of
stuff between the devices, you don't need DMA on the host machine for this,
and SCSI is more flexible and faster than IDE in it's old form. If you look
at the modern UltraDMA-drives, IDE definitely IS much faster, and even cheaper,
so here is the only missing thing the flexibility of SCSI. And Ultra-SCSI has
lots of them, including a very good performance.

But is an IDE drive on the QBus really the right thing for these boxes ? Ok,
it's cheap, but it's not the right style :-) If you want to do it real good,
just adapt a 386 mainboard including onboard-IDE to the QBus, then you might be
able to write the MSCP stuff on this "controller"... TQK50 also
uses an 186 CPU.

so long... Michael