[Simh] DECtape simulation for 36b tapes on PDP-8?

[Johnny Billquist]

On 2013-03-12 11:50, Johnny Billquist wrote:
> On 2013-03-12 05:53, Ian King wrote:
>> On 3/11/13 6:00 PM, "Ian King" <IanK at vulcan.com> wrote:
>>
>>> Hi folks,
>>>
>>> I'm doing some work where I need to build some DECtapes for a PDP-10,
>>> using a PDP-8 and PIP10.  Long story short, I decided to use SIMH to test
>>> some ideas but I cannot access a PDP-10-formatted DECtape mounted on the
>>> emulated TC08/TU56.  The emulator simply hangs.  I also tried just
>>> creating a new 'tape' in 18/36b mode and looking at it with PIP10, again
>>> resulting in a hang.
>>>
>>> Do you know of a way to hold one's mouth to get a PDP-10 DECtape to be
>>> recognized on SIMH?  :-)  Thanks -- Ian
>>>
>>> I'm done with this two-bit town.  Show me a twelve-bit town ­ now we're
>>> talking.
>>>
>>> Ian S. King, Sr. Vintage Systems Engineer
>>> Living Computer Museum
>>> A presentation of Vulcan, Inc.
>>> http://www.livingcomputermuseum.org
>>>
>>> _______________________________________________
>>> Simh mailing list
>>> Simh at trailing-edge.com
>>> http://mailman.trailing-edge.com/mailman/listinfo/simh
>>>
>>>
>>
>> To clarify: I'm trying to access PDP-10-formatted DECtape on the PDP-8
>> emulation, using PIP10.  A couple of (thank you so much) replies made me
>> realize my statement of the problem was ambiguous.  -- Ian
> 
> I understood you the first time. My big question would be if you are
> sure the TC08 emulation is good enough. PIP10 uses its own code to
> handle the drive, and uses it in ways no other PDP8 code likely do. It
> definitely would test the emulation much harder than anything else I can
> think of.

By the way, another question is how your PDP-10 formatted tapes got onto
the host running simh, and connected to the simulated TU56. Did you have
some real PDP-10 DECtapes that you transferred somehow? If so, then how?
Or did you get them using some PDP-10 simulator to create them on a
smimulated DECtape on the ten side?
Are the simulated tape format in the files compatible? Exactly how do
the format look like? DECtape as such have a rather free form in some
ways. It's not totally clear to me in which way I would represent these
tapes on disk in a way that would allow me to operate correctly on them.
Especially if we want to deal with both 12-bit and 18-bit formatted
tapes. This can get rather hairy. On the real systems, this is mostly
done in hardware, but it is rather fiddly.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol