[Simh] Largest VAX / PDP disk sizes

[Shoppa, Tim]

All of the PDP-11 and VAX operating systems that I know of (with one exception) that can talk
to MSCP disk drives, will talk to arbitrary sized MSCP disk drives. Maybe they cannot use all the capacity
depending on the file system. (RT-11 has 65K blocks max per file system, ODS-1 depends on the
version of RSX, etc.)

The exception that I recall is MicroRSTS, which actually insists on seeing a recognized device name with
known geometry. Maybe, just maybe, MicroRSX had some similar limitations, insisting on seeing
RD52's or RD53's and refusing to work otherwise.

XXDP diagnostics are device specific anyway.

MSCP was the breaking point of getting away from tracks, cylinders, sectors and
just thinking of a disk as a big bunch of sequentially numbered blocks. A big win for the late 70's!

SIMH supports arbitrary sized MSCP disks. RCT tables won't match any real drive but who cares?
We do not want to go back to bad block replacement in the OS's device handler.

Tim.


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