[Simh] Certainly a silly question

[Armistead, Jason]

It would be a useful enhancement if the host operating system could notify SIMH when it wanted to change a disk or CD image file over.  Maybe this requires SIMH to listen to a given port (emulated terminal serial I/O or via TCP/IP).  Terminal ports might be easier for host scripting (something delivered with SIMH and installed on the guest OS).  Obviously, if we want to prevent the host from doing this, it should be configurable as such.

Done right, we could have the entire set of VMS layered product and documentation CDs, plus DECUS tapes, etc. all available for loading on an as-needed basis (or the equivalent for whatever guest OS takes your fancy).

This would seem better than dismounting the CD inside the guest OS, then pausing SIMH, changing the disk image over, restarting the guest again and mounting the CD again.  It also seems more manageable than creating dozens of disk devices, only to run out of, or be limited by, the host's limited number of  devices as Marc has.

And, if we have a good solid interface, then there's no reason people couldn't "roll their own" guest-side program to make it as fancy, or as simple, as they need it to be.

Something for the next SIMH version perhaps ?


~~ Jason

-----Original Message-----
From: simh-bounces at trailing-edge.com [mailto:simh-bounces at trailing-edge.com] On Behalf Of Marc Chametzky
Sent: Friday, 4 May 2012 2:50 PM
To: Craig A. Berry
Cc: simh at trailing-edge.com
Subject: Re: [Simh] Certainly a silly question

In my case, I would also have liked to have a simpler way to set up a series of disk volumes that were set up as an array of RRD40s for a CD collection I have mounted on my VAX (VMS). Right now, I'm filled up with DUA0-3, DUB0-3, DUC0-3, and DUD0-3, giving me 16 total volumes (used as
3 virtual hard drives and 13 virtual CD drives).

I think the limitation here is in the hardware devices available to VMS itself. The controllers being emulated (and thus the matching device
drivers) probably didn't support more than 4 devices per controller, so that's why we're limited in this fashion.

--Marc