17 Sep
2020
17 Sep
'20
12:06 p.m.
On Sep 17, 2020, at 2:11 PM, Chuck Guzis via cctalk
<cctalk at classiccmp.org> wrote:
On 9/17/20 8:56 AM, Jon Elson via cctalk wrote:
Even there you might find some oddities.
A RSTS distribution tape, for recent releases, begins with some DOS-11 formatted data,
i.e., 14 byte file header and 512 byte data. That is followed by ANSI labelled data, so
80 byte file labels and data in a VMS-style backupset, 2048 byte blocks I think.
paul
This is not necessarily true. Many systems can
handle "VBS" (Variable
Block Sequential) tape files.
But, yes, fixed block size is more common.
"Hybrid" files are quite common, where all blocks are the same size, but
for the last one. Or, in the case of some PDP 11 tapes, there's a short
record containing file name, etc. followed by the file data in
uniformly-sized blocks, but for the last one in the file.