9 track tapes and block sizes

Jeff Woolsey jlw at jlw.com
Thu Sep 17 20:13:14 CDT 2020

> On 17/09/2020 07:38, Dave Wade G4UGM via cctalk wrote:
> >/The docs for SIMH .TAP files are here:- />//>/http://simh.trailing-edge.com/docs/simh_magtape.pdf />//>/be careful as there are also non-SIMH .tap formats />//>/In the IBM Mainframe emulation world there is also .AWS, an IBM format />/introduced with its P390 Microchannel Mainframe card />/and .HET a Hercules extension to .AWS which allows compression />//
> vtapeutils is quite handy for translating between (or listing) a few of
> the emulated tape formats. It supports AWS, TPC (2 byte record headers)
> and TAP (Simh - 4 byte record headers).
> https://sourceforge.net/projects/vtapeutils/
> I've used TPC on RSX-11M and VMSTPC on VAX/VMS to read 9-track tapes.
> Then I used vtapeutils to convert from TPC to TAP format for Simh.
> Matt
I have over 1000 TAP images in my collection, so I thought I'd give this
a whirl.  It's handy for a quick summary of what the TAP image is. 
However, documentation is a bit light, as is its robustness for corrupt
TAP images (of which I have plenty), although it seems forgiving of
unpadded blocks (unlike another, stricter tool I could mention).

For unlabelled tapes, it lists block count and min and max block size
for each file. Nice. But it does not do that for labelled tapes; instead
they get the labels that enclose each dataset decoded, and the number of
blocks is reported and checked.  A warning is printed if the actual
block count differs.  Sometimes this warning is incorrect, reporting 0
or a large negative number (-17342528 usually) of blocks.  It is usually
correct for those of my tapes that have duplicate blocks (which I don't
expect it to detect/report otherwise).  The 0s might be extraneous
EOF1/EOV1 labels.  The negatives might be extraneous tapemarks.  Or
stuff past EOI.

It would be nice if it printed the name of the TAP file in its report.

Built from source (edited Makefile to add $(CC) ).    I didn't try vtapecp.

Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
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"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel.  -Crow on solitaire

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