[Simh] Problem with reading tape with PDP-11 SIMH

[Alan Frisbie]

Mark,

> > The difference with the simulator vs the real hardware is that,
> > in general the TPC program may never get a chance to queue more
> > than one I/O to the device since the first operation will likely
> > complete BEFORE control returns to the user mode program.  This
> > may stress the user mode program in ways which it never saw when
> > real tape operations took many milliseconds (or seconds).
>
> An excellent point, which I had not considered.   I will have to
> do some exploration in this area.
>
> > If this is happening, some adjustments to the behavior of the
> > TS device can potentially be made to slow it down.  Try
> > "sim> DEP TS TIME 5000" or change 5000 to some other large number
> > (the default is 10).
>
> I will try this and let you know what happens.

I tried this, and it appears to fix the problem!   At least TPC
completes and has created a file of approximately the right size.

Thank you for saving me lots of debugging time.

Now the next problem:

When I try to create a new SIMH "tape", I am getting a "File open
error", but no other information.   How can I find out what the
problem is?   Here are the commands I am issuing:

sim> set ts0 format=tpc
sim> show ts0
TS0     not attached, write enabled, TPC format
        unlimited capacity
sim> attach -n ts0 newrsx11s.tpc
File open error
sim> 


Thanks,
Alan Frisbie