The four ports is not arbitrary. SimH simulates actual hardware. DEC
never built a backplane MSCP controller with more than four ports.
If you want to extend the current RQ simulator to include third party
boards (either SMD-based emulators or SCSI-based emulators), feel free
to add an appropriate mode switch. I don't know what controller ID these
third party boards returned, though, nor do I know how VMS determined
the number of ports per controller.
I think it would be better to understand why VMS is waiting to mount
additional discs. Alternately, just create bigger discs and have fewer
of them.
/Bob
On 6/23/2019 12:00 PM, [email protected] wrote:
This is, though, another slight silliness in simh. The limit to 4 disks
per controller is very artificial. The UDA50, KDA50, and maybe some
other controllers only have four actual, physical ports, which limited
them to only have four disks per controller. However, MSCP itself do not
have such a limitation, and common SCSI controllers for these machines
which use MSCP allows more than four disks on a controller, and most
software (at least RSX and VMS) also do not limit themselves to only
configure max four disks on a controller. I wish simh didn't put such
arbitrary limitations in. simh also decides on unit numbers by itself,
which could also have been nice to be able to choose.
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