12 Apr
2024
12 Apr
'24
3:57 p.m.
On Fri, 2024-04-12 at 15:13 -0400, Paul Koning via cctalk wrote:
Yes, variable length "sectors", you'd
specify in the JCL what you
wanted for blocksize of that particular file. If I remember right,
the block length could vary from one block to the next,
In about 1998, I had to move some data from a VAX to a Unix machine
(HP-UX). I copied the data using FTP. What I didn't know in advance was
that it was binary (mostly numeric, oddly 360-format floating-point
numbers and an EBCDIC header), with variable length records. The VAX
Record Manager, sometimes affectionately known as the Record Mangler,
kept track of the record lengths which, of course, FTP didn't carry
over to the Unix machine. Then I found out that record length was one
of the desiderata for the record type. I happened to know one of the
engineers responsible for the originalk software, who volunteered to
change the format so the record length was within the record, before
the VAX was retired. He said "I don't have the files any more, but I
have the listings and I can punch it in again. Because keypunch
machines were long gone by then, I assume he "punched it in again"
using his VT-102.
Apart from those, I only ever remember seeing fixed
size sectors,
though the actual lengths might be strange -- like the CDC mainframe
disks with sectors of 322 12-bit words.
Or Univac disk formats, with FASTRAND™ sectors of 28 36-bit words and
tracks of 64 sectors.