VME CAMAC SHD connected via SCSI - is it possible?

[ken reed]

We currently have a specialised piece of hardware (a CAMAC Serial
Highway Driver) plugged into one of our Sun's VME slots. Now it looks
like we may want to connect this device to machines (30 or so of them)
that do not have VME slots (for reasons of cost).

We don't want to re-design the VME card so the simplest and cheapest
solution seems to be to use a SCSI-to-VME converter and connect the
SHD in via a SCSI controller. We plan to dedicate a controller for
this interface so that we run no risk of disturbing the disks
connected to the other.

I've written the UNIX device driver for the current VME set-up and am
starting to read-up on SCSI to do the new driver. However, at the
moment I know next to nothing about it and I thought it might be wise
to ask if we're trying to do something silly before expending too much
effort on this project. I have two specific question areas (hence this
posting to 2 groups) that I would be *most* grateful for any
comments on.

1: (for comp.unix.internals) Is there any reason why there shouldn't
be a separate SCSI kernel driver operating independently of any
existing one driving discs, etc? I can't see any reason why not but,
only having written one driver so far, my knowledge is limited.

2: (for comp.periphs.scsi) Are we being silly in trying to use SCSI in
this way? What is needed is the ability to transfer data (with firmware
help in the SHD) between the UNIX box and the VME SHD card and receive an
interrupt from the SHD. From what I've read so far it seems reasonable
but I've only ever seen disks and tapes plugged in via SCSI.

The real pain is that we don't know (yet) what type the target
machines will be, so bus adaptors (eg VME-SBus) are not a current
option.

As I said, any comments at all would be most appreciated.

By the way, this is my first ever posting so, if I've messed up and
this turns up in inappropriate groups, please forgive me.

Many Thanks

Ken Reed
JET Joint Undertaking             |   kr%jet.uucp at ukc.ac.uk (world)
Abingdon, Oxon, OX14 3EA, UK      |   kr at jet.uucp         (UK only)
-- 
  Ken Reed                          |   tel: +44 235 528822  ext 4995
  JET Joint Undertaking,            |   kr%jet.uucp at ukc.ac.uk (world)
  Abingdon, Oxon, OX14 3EA, UK      |   kr at jet.uucp         (UK only)
- Disclaimer: Please note that the above is a personal view and should not 
  be construed as an official comment from the JET project.