[Info-vax] Replacing SCSI disks in PS433AU for VMS

johnwallace4 at yahoo.co.uk johnwallace4 at yahoo.co.uk
Fri Oct 2 13:04:00 EDT 2020


On Friday, 2 October 2020 17:38:29 UTC+1, Chris Townley  wrote:
> On Friday, October 2, 2020 at 4:51:22 PM UTC+1, John H. Reinhardt wrote:
> > On 10/2/2020 10:45 AM, Chris Townley wrote:
> > > On Thursday, October 1, 2020 at 7:15:01 PM UTC+1, johnwa... at yahoo.co.uk wrote:
> > >>> Chris
> > >>
> > >> Bear in mind that what's usable as an SRM-bootable VMS system disk is
> > >> likely a subset of what's usable as a data disk in the same box.
> > >> Apologies if you already knew that.
> > > 
> > > Interesting point. Any ideas what restrictions for a VMS boot disk?
> > > 
> > > CHris
> > > 
> > 
> > I had a PWS433AU at one time.  Being SCSI, being SRM-bootable is a lot less dependent on the disk than the controller.  Not like the old MFM and EDSI disks.  I don't recall if the PWS433 had an on board SCSI controller.  But any of the typical SCSI cards from that era will work and pretty much any SCSI drive is bootable.  The PWS433 doesn't have the limitation that certain MicroVAX 3100's had on boot drive size.
> > 
> > -- 
> > John H. Reinhardt
> 
> Thanks
> 
> The spec shows the built in SCSI controller as:
> 
> > SCSI adapter: 32-bit ultra-wide SCSI (UW-SCSI)
> > adapter that supports 50-pin narrow, 68-pin wide, and 68-
> > pin ultra-wide SCSI devices.
> 
> I understand this is a Qlogic 1020A Fast SCSI adapter
> 
> I also have another wide controller for a BA356 externally, but I get too many errors on that for a boot disk. I think the cable is too long
> 
> 
> Chris

Does your spec match your particular system? From memory, there were 
at least two generations of PWS433au systems. Wikipedia has some 
words on the subject; 

Traditionally I'd suggest finding a QuickSpec for the model but 
there isn't an obvious one at the moment.

There is a PWS User Information document at
https://web-docs.gsi.de/~kraemer/COLLECTION/DEC/alunxuib.pdf
which may be helpful but doesn't have much to say on this particular 
subject.

Basically if you want it to boot VMS from a SCSI drive, SRM console 
(in ROM) needs to know about the SCSI adapter. This typically led to 
Qlogic 1020 or 1040 adapters, either add-in or built-in. Beyond that, 
the VMS Software Product Description for your chosen VMS version 
might shed some light on what adapters and drives were supported. 
What *works* (at least in terms of drives) would often be a bit more 
generous, so long as you don't get too ambitious.

This SCSI magick was always a bit of a maze to me, and it's been a 
long time. 

Best of luck.



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