[Simh] SIMH tape images to real tapes

[Larry Baker]

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov



On 15 May 2014, at 5:30 PM, Cory Smelosky wrote:

> On Thu, 15 May 2014, Larry Baker wrote:
> 
>> Cory,
>> 
>> I wrote a MagTape Duplicator (MTD) program decades ago in Fortran.  It runs on RSX and (VAX or Alpha) VMS.  Here's the VMS HELP file:
>> 
> 
> I have fortran installed so that should work.
> 
>> I used to use it to rescue tapes by splicing pieces together when there were errors, like corrupted ANSI labels.  (By the way, two consecutive tape marks is not necessarily EOT.  An ANSI labelled tape containing an empty file -- ala "touch file" on Unix -- has no blocks in the data portion.  The tape will have ..., HDR labels, TM, (no data blocks) TM, EOF labels, TM, ..., EOF or EOV labels, TM, TM.  The end of an ANSI labelled tape is two consecutive tape marks after the last set of EOF or EOV labels.)
>> 
>> If you modify MTD to use the SIMH on-disk tape image format instead of my own, it should work fine.  There are simple routines that do disk file I/O, like DKOPN (open an image file), DKPUT (put a tape record), DKGET (get a tape record) DKCLS (close an image file).
>> 
>> I'm pretty sure I've asked before, but I forget.  Where is a repository I can upload my code to share?  What format is preferred?
>> 
>> As far as TK50, I always used them exactly as 9-track tapes on RSX and VMS.  From the point of view of the software, you get blocks and tape marks, just like a 9-track.
>> 
> 
> Cool.  So once I figure out the SIMH tape format I'm good to write an image to tape with this?

I think the answer is yes.  This code is from very long ago when there were no OPEN keywords to permit Fortran to read/write C files.  I'm pretty sure I just read/write Fortran unformatted data files, where each record in the file is a tape block.  Thus, tape marks are simply zero-length records.

How much or a hurry are you in?  What is your OS version on the machine with the TK50?  We have a VAX running OpenVMS V6.2 and an Alpha running OpenVMS V7.2-1 in a dual-node cluster.

> -- 
> Cory Smelosky
> http://gewt.net Personal stuff
> http://gimme-sympathy.org Projects

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