[Simh] Initializing disks (triggered by the "Something Strange with RK05" chain

[Mark Pizzolato]

On Wednesday, February 12, 2020 at 4:22 PM, Paul Koning wrote:
> > On Feb 12, 2020, at 5:37 PM, Mark Pizzolato <Mark at infocomm.com> wrote:
> >
> > Recent versions of the simh PDP11 will correctly auto size (RL01 vs RL02) disk
> > containers that have or don’t have the DEC STD 144 bad block table at the end
> > of the drive as long as the disk image has an RT11 file system on it.  If it has an
> > RT11 file system that fact will be reported.
> >
> > The prompt “Overwrite last track? [N]” is actually asking a question about
> > whether the DEC STD 144 bad block table should be written.  The default of
> > “[N]” will create a 0 sized container file on simh v3.x and before.  On simh 4.x,
> > the container file will be created to the full size of the respective drive without
> > regard to the answer to the “Overwrite last track? [N]” question.
> >
> > Maybe the message:
> >
> > ?DUP-F-Size function failed
> >
> > Happens when an empty container is provided (without a DEC STD 144 bad
> > block info)…
> >
> > -          Mark
> 
> That could be, but shouldn't the device type, if supplied, control what is
> reported?  And presumably that has a default, so if the container isn't pre-
> extended the default type would apply.

That would be the case if the container had no recognizable file system 
on it, otherwise the size of the file system overrides.  

> The file system based auto-sizing lets SIMH figure out what the type is given an
> undersized container and a file system it knows that allows it to deduce the
> size.  But without that you should still be able to force the size, right?

Explicitly stating the drive type with: SET RLn RL01|RL02 disables autosizing.  

However, with autosizing disabled, if a file system is recognized in the container, AND the file system size exceeds the size of the specified drive type, the attach fails with an explanation to this effect. Hopefully you wouldn't want a different behavior under these circumstances.

- Mark