🚀 go-pugleaf

In <7349@idunno.Princeton.EDU> bill@tremor.Princeton.EDU (Bill Wichser) writes:

>We are considering upgrading a uVax in our department to a RISC machine.  
:-)
>Unfortunately, the funding does not permit too much more than a CPU.  
:-(

>The current
>configuration on the uVax has two ESDI drives (Maxtor EXT4380 and CDC Wren6) 
>which we would like to salvage and use on the new system.
>Is there a way to convert these disks to SCSI?  

You need a SCSI bus ESDI disk controller. I think OMTI made them at one time,
shop around. 

>It seems there should be an upgrade to the controller board that sits 
>on the drive itself.  Is this something the drive manufacturers in fact have?

Probably not, and almost certainly not as an upgrade. Although it wouldn't
hurt to ask (call Maxtor, I own stock :-) It's doing terrible :-( )

> I have also heard mention of a controller from Emulex that sits on the 
>SCSI bus and makes the translations from SCSI to ESDI.

That's the guy! one of those.

>How much slower is this than a board upgrade to the drive 
>(if such a thing exists)?

What that board does is convert SCSI commands into ESDI commands, and
convert byte data into ESDI streams. The overheads possible are:
1) You will not be able to overlap data transfer, and you may not be
able to overlap data transfer with seek. You WILL be able to overlap seeks.
2) There is command interpret overhead, which is astoundingly large
for some SCSI controllers.

Both of these are also available on your current Q-bus ESDI controller,
which, if it comes from DEC, is probably not the most blindingly fast thing
in the universe.
Except for overlapping disk-to-onboard data transfers, you get all the
same opportunities with the controller on the disk option.

Martin Golding    | sync, sync, sync, sank ... sunk:
Dod #0236         |  He who steals my code steals trash.
Blechtrottel CPU with many megs...
{mcspdx,pdxgate}!adpplz!martin or martin@adpplz.uucp