[Info-vax] Copying VMS SaveSet Under Windows

[Bob Eager]

On Sun, 21 Nov 2010 20:50:44 +0100, Michael Kraemer wrote:

> JF Mezei schrieb:
>> About ANSI tapes:
>> 
>> Question: does the tape drive itself signal end of file and end of tape
>> ? Or just end of tape ?
>> 
>> or does the tape automatically  skip inter block gaps and return block
>> after block, with only end of tape being signaled ?
> 
> there's nothing magic about ANSI tapes.
>  From the tape drive's (and UNIX') point of view,
> the files on tape are still sacks of bytes, separated by single tape
> marks, and a double tape mark signals the EOT.
> It's just that some OS's (e.g. VMS) wraps each tape file in an extra
> header
> and an extra trailer file containing additional file info (name, date,
> recl etc), and the whole tape is assigned a volume label recorded
> somewhere in the first header. It's not rocket science, but of course
> requires some extra work to teach a Unix system to read that information
> - if anybody would be interested. I did such things about twenty years
> ago to facilitate data exchange with the non-DEC world. DEC Unices
> (Ultrix, OSF/1) have the "ltf" utility on board, but iirc it has limited
> capabilities (i.e. no multivolume support etc.)

It's a pretty trivial job, because one doesn't have to teach a UNIX 
system (or a Windows one) to understand it. One reads the tape, stores 
the data in each block, and remembers where teh tape marks are. The SIMH 
'tape file' format is easy, and *that* is what one is aiming for. Then 
you attach it to the simulated VAX as a tape drive, and just use it...



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