Recovering 4mm tar tapes

[Craig Ruff]

> On Sep 12, 2016, at 11:00 AM, cctech-request at classiccmp.org wrote:
> 
>  Is the 2nd tape just bad and can't be read?  Or do I need a 
> slightly different tape drive?

It may be bad or perhaps it was written with a larger block size?  I don’t recall what tar does if the tape was written with a record size larger than the default.  You might try using

	dd if=/dev/st0 bs=65532 of=...

on the tape to see if you can read it at all.  I don’t recall what the maximum record size on these tapes are, but it seems like it isn’t a full 65KiB.  Also, make sure the drive is not configured for fixed block mode.