Hi Allison,

why I mentioned this MSCP and TMSCP prtocolls is only that we have the
chance to boot from this disks. It is VERY fine with me, not to need this
protocolls, and make a new one, that is easy to implement, and easy for a
driver in NetNSD.

This idea with the IDE drives, was for a short time in my mind, but ....

I like SCSI better. put all your old disk in a system without thinking of
this very different stuff that is made on IDE. (probably someone want to
plug in a SoundBlaster compatible CR-Rom drive on this controller ?) I know
this is not exactly a IDE problem ...

But probably i do both ... 
 
cheers,
emanuel	


P.S. Anyone has a spare documentation of the DRV11-B and DRV11-P modules ?

----------
> From: Allison J Parent <allisonp@world.std.com>
> To: port-vax@netBSD.org
> Subject: Re: SCSI on Q-bus
> Date: Wednesday, February 04, 1998 6:42 AM
> 
>  
> <> At 08:51 AM 2/2/98 -0700, emanuel stiebler wrote:
> <> >What makes this scsi so expensive ?
> <> >Is there a patent on this MSCP, TMSCP protocols ?
> <> >
> <> >I'm thinking about developing one for the q-bus, should be cheaper
tha
> <> >.., and i could use my disks here.
> <> >(its not my first one, i build such stuff on vme-bus before)
> 
> First off the controller does not have to do MSCP unless you wish to use 
> DEC software.  So by eliminating that it means that NetBSD will provide
> direct support.  Same applies to the VS2000.  There is no need to emulate
> MSCP there is a need to present a logical interface to the kernel and
> deal with bad sectors but that I presume is a driver problem.
> 
> Second, why scsi?  Why not IDE it's cheaper hardware, capable of better
> performance than the RQDX3/mfm drives and requires a simpler controller
> than SCSI.  IDE offers one thing that SCSI does not.  New surplus 1GB 
> drives can be had for less than $100.  If IDE were used a fair 
> amount of the basic logic on the DRV-11B could be done using a DRV-11P 
> foundation module as a proto and then commit to circuit board layout.
> 
> What the board must have/do:
> 
>  DMA for transfer performance:
>   SCSI/IDE would be slow with PIO, though IDE would be better.
>   DMA for Q-bus only support 22bit(4Mb) transfers.
> 
>  IDE or SCSI bus
> 	IF SCSI likely local intelligence (z80,8751,8086, whatever) 
>           will be needed to manage the protocal.  This adds cost and
> 	  design complexity.
> 	IF IDE only a hardware interface with DMA will be all that's 
> 	 needed.  
> 
> Drivers to actually make the board work for netbsd.
> 
> Both IDE and SCSI drives are smart enough to do part of the sector 
> sparing work for a OS.  However if it is inadaquate there will have 
> to be a protocal for that in the driver/kernel as well.  In either case 
> the interface would be fully understood and there would be no excuse 
> for a weak driver.
> 
> IDE offers a far lower cost interface.  It should be considered.
> 
> 
> Allison