[Simh] SIMH tape images to real tapes

[Larry Baker]

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:

> USGSMTD.HLP
> 
>      MTDup duplicates magnetic tapes without interpreting their contents.
> The copy may be directed to another tape drive, or to a tape image inside
> a disk file.  Either the entire tape or selected portions may be specified
> in the copy operation, with or without rewinding the tape first.  An optional
> verify pass will validate the copy, provided the entire tape is copied.
> 
>      MTDup takes a command line of the form:
> 
>           >MTD[up] /HE[lp]     or
> 
>           >MTD[up] outfile[/sw...]=infile[/sw...]
> 
> where outfile specifies the output tape drive or tape image file and infile
> specifies a the input tape drive or tape image file from a previous run.
> 
>      Type HELP MTDUP SWITCHES for a description of the available switches
> and their defaults.
> 
> 2 SWITCHES
> 
>      The following switches are available for MTDUP:
> 
>           /HE[lp]      Print command summary
>           /VE          Verify copy
>           /CM[p]       Compare only, do not copy
>           /ER[rors]:count  Maximum number of tape I/O errors allowed
>           /-ER[rors]   Inhibit error checking
>           /FR[om]:file[:block]  Begin transfer with file and block number
>                        specified, in decimal
>           /TO:file[:block]  End transfer with file and block number specified,
>                        in decimal
>           /AP[pend][:file[:block]]  Append output to existing tape, after
>                        file and block number specified, in decimal
>           /CD          Set a 7-track drive for core-dump mode
>           /DE[ns]:density  Set output tape density, e.g., 1600
>           /BL[ocks]:initial_size[:extend_size]  Disk file allocation
>           /CO          Make disk file contiguous
> 
>      The default command line is
> 
>           MTD>MM1:/-AP/DE:1600=MM0:/-VE/-CM/ER:1/FR:1:1/TO:9999:9999-
>                                    /-CD/BL:100.:50./-CO
> 

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.

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



On 15 May 2014, at 2:11 PM, <simh-request at trailing-edge.com> <simh-request at trailing-edge.com> wrote:

> Message: 4
> Date: Thu, 15 May 2014 16:38:25 -0400 (EDT)
> From: Cory Smelosky <b4 at gewt.net>
> To: simh at trailing-edge.com
> Subject: [Simh] SIMH tape images to real tapes
> Message-ID:
> 	<alpine.OSX.2.00.1405151636150.492 at melanie.gimme-sympathy.org>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
> 
> 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