All this talk about magtapes brought some memories to
the fore.
While a single tape drive was the rule for personal computers, it
certainly wasn't that way for mainframes. In particular, one very
important aspect was sorting (and, by extension, merging). The wonder of
a polyphase (or better yet, oscillating) sort running on a bank of 8 300
ips drives was mesmerizing.
Undoubtedly, the folks before me who spent their time shuttling trays of
punched cards around an IBM 082 have a similar reaction to the "easiness"
of tape sorts as compared to card sorts...
I remember a regular job (every week....) in my servicebureau where I had to
sort about 40.000 200-byte records on a DOS machine. DOS did have a SORT
command, but it was horribly insufficient.
I therefore had to get back to my experience as IBM 82 operator (!), and do
it more or less that way. The first stop was to create x files, each
containing about 1000 key fields. When the input was read, I would sort one
keyfile at a time internally and write it to a new file. After the sorting,
I merged two indexfiles and write a new file, etc. When all indexfiles were
merged into one, I found the respective full records, and wrote the output
file.
It took about 15 minutes or so for the whole job, but the customer was
happy.
/Nico