Microvax II

From: ajp166 <ajp166_at_bellatlantic.net>
Date: Fri Oct 13 22:39:38 2000

From: Jerome Fine <jhfine_at_idirect.com>


>I doubt very much that the answer is YES! Otherwise, it would have been
>easy to produce the 3rd party SCSI host adapters and there would have
>been a lot more competition - even with the $ US 100 license fee.


the key is not to design a VMS driver so MSCP makes you immune to that.
If your willing then a bare SCSI interface is very doable, but the driver
will
be harder and slower even with DMA. In VAX products there was
competition
around storage perfomance even back then.

>Now I have heard of someone attempting to produce a Qbus controller
>for an IDE drive that would not even be MSCP - and probably put the
>IDE drive right on the controller - not that MSCP would be all that


There is a design out there, crude and PIO only. It would certainly work
as IDE can PIO pretty fast. the only thing that makes Q-bus the least
bit
hard is that it has a read before write, that can mess up some register o
riented devices with an out of sequence read.

Allison
Received on Fri Oct 13 2000 - 22:39:38 BST