lunchbox VAXen, was Re: [HECnet] Introducing myself... and my little network

[Dave McGuire]

On 06/07/2012 07:42 PM, Bob Armstrong wrote:
Lunchboxes! :-)   And there are images for new boot ROMs available for
those
which will allow you to boot from the on-board SCSI host adapter, ...

  I've heard of this, but I haven't seen it.   As I recall, the onboard SCSI
adapter uses programmed I/O (no DMA!) so it's really slow.   For a TK50
nobody would ever notice, but for the system disk it's a problem.   Better to
cluster boot one, diskless.

  That'd likely be faster!   I'm thinking of the case where one would
want a standalone machine, and the XT2190/RD54 is as capacious as MFM gets.

  Having never run a '2000 via its SCSI host adapter myself, only the
MFM interface, I'd have to wonder whether the bottleneck would be that
PIO-accessed NCR5380 or the 78032 itself!

  FWIW, an RD54 isn't necessary.   The 2000 can easily be convinced to use
_any_ MFM drive, DEC or not.     You can get VMS V4 on a 30 meg drive, maybe
even 20, if you're determined.   Long ago I wrote up a little description of
all the VS 2000 disk formatter parameters, what they meant, and how to fake
them for non-DEC drives.   Google ancient Usenet postings if you're
interested.

  I've had a copy of that archived away for many, many years. :-)

                      -Dave

-- 
Dave McGuire, AK4HZ
New Kensington, PA