[Simh] fprint_sym and parse_sym limitation

[Mark Pizzolato - Info Comm]

On Monday, September 14, 2015 at 6:20 AM, Paul Koning wrote:
> > On Sep 14, 2015, at 12:53 AM, Mark Pizzolato - Info Comm
> <Mark at infocomm.com> wrote:
> >
> > ...
> > Paul said:
> >> We have a context pointer in
> >> the device, but not in the unit (I ended up having to abuse the
> >> filebuf for that).
> >
> > Reusing the filebuf could certainly be used for an arbitrary context variable if it
> isn't being used otherwise.  Alternatively fileref can optionally also not be a FILE
> *.  When it isn't a FILE *, the unit->dynflags UNIT_NO_FIO flag should be set.
> When set, it becomes a unit specific void * which can be used for context or
> anything else.
> 
> Ok.  This is another example of something undocumented.

True.  

Meanwhile, I was thinking this over one more time  and I realized that I had forgotten that there are already 2 user/device specific void pointers in the UNIT structure:

	uptr->up7
	uptr->up8

Do with them as you wish.

- Mark