[Simh] SIMH tape images to real tapes

[Clem Cole]

I wrote one of these a long time ago for Tru64, but I do not think I still
have it.  The concept is easy:
http://simh.trailing-edge.com/docs/simh_magtape.pdf

But the problem is it becomes extremely driver specific.   You need to know
what marks the driver is going to write for you - which is highly OS
dependent - as well as what the devices does behind the scenes which is
highly device dependent.  I was going to 9-track and I know the details for
all of that, but I have not idea how TKxx wrotes tape marks (I always
avoided them as a "bad idea").

In 9-track world, the end of each file is mark as a single meta record
(tape mark),  Two in the row marks end-of-tape.   So the when you write a
take the driver check to see if its at start of tape and if not, has to
backs up over the last tape mark and then start writing.  On close it
writes 2 tape marks.

QIC tapes do not work that way.  Exabyte and DAT are closer to 9-track in
rules, but I've forgotten most of the details and I do remember there was
something funky about the original DECtape but those bits in my brain have
long rotted away.  You really should open the driver for the TK50 and see
if you can grok it.  Look at the open and close code very carefully.

Clem




On Thu, May 15, 2014 at 4:38 PM, Cory Smelosky <b4 at gewt.net> wrote:

> Hello all,
>
> Googling around only seems to want to show me how to copy real tapes to
> images.  I need to copy a SIMH tape image to a real tape!
>
> I seem to recall SIMH including a utility for this...but I could be
> mistaken.
>
> I will need a utility that will run on VMS (VAX) as I need to use a TK50
> to make a TK50. (Unless someone wants to doante a TK70. ;) )
>
> --
> Cory Smelosky
> http://gewt.net Personal stuff
> http://gimme-sympathy.org Projects
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