[Simh] More than 4 Drives ?

[Glynn Stanton]

Thanks Tim, unfortunately didn't work, still get the "Unit Disabled" after
upping RQ_NUMDR and recompiling. Also tried upping RA_NUMCT but to no avail.

Perhaps my question is more "How do I add another controller" if 4 is the
max per controller.

 

-----Original Message-----
From: Tim Shoppa [mailto:shoppa at trailing-edge.com] 
Sent: Monday, May 09, 2005 8:44 PM
To: simh at trailing-edge.com; glynn at paniglynn.com
Subject: Re: [Simh] More than 4 Drives ?

> Seems that simh is limiting me to having a maximum of 4 drives, rq0 to 
> rq3.  When I try and define an rq4 I get a "Unit disabled" error".

True DEC MSCP controllers only supported up to 4 drives per controller.

The MSCP protocol allows more than 4.  And there's some OS support (RT-11,
RSX-11 with a patched SYSGEN, VMS out of the box) if you have a controller
with more than 4 drives.

I think if you rebuild simh with RQ_NUMDR (in module pdp11_rq.c) set to a
number bigger than 4 it oughta work just as the real hardware.

There were non-DEC MSCP controllers that did allow more than 4 MSCP drives.
e.g. CMD 440, Sigma/Webster WQESD, etc.

Tim.