cclist at sydex.com
Tue Aug 29 12:01:04 CDT 2006
On 8/29/2006 at 8:08 AM Don wrote:
>IMO, this was a mistake. It forces the OS to know too much
>about the applications that run on it -- instead of being a
>resource manager. I.e. it should implement mechanisms, not
Okay, this is drifiting OT, but I can't let this go by unchallenged.
It merely incorporates the nasty business of blocking and formatting
records into a standard set of routines. They don't have to be run at the
supervisory level, but convention should dictate their use. The beauty is
that data interchange among applications gets easier--and you don't have
the run-time library for a particular language implementing its own idea of
what a file full of ASCII strings is and being compatible with nothing
Your example of a COBOL program writing source for a FORTRAN program thus
works, as long as the COBOL program doesn't use datatypes that are
completely unknown to the FORTRAN world (e.g. COMP-3 numbers).
Cyber Record Manager (CRM) was introduced into the CDC NOS world sometime
during the 70's and it made a big difference in application code. If your
program, for example, had to read a tape full of 7000 SCOPE W-type records,
you could simply declare the tape (via job control statements) as
containing them, instead of having to write a bunch of code to decipher
them. And one application's idea of what an ISAM file was is assured to
be the same as another's.
For the diehards, you can always declare a medium as containing raw bits
and wrestle with them in your applicaton code. But for most applications,
there's no reason to do this.
How many ways are there of representing variable length character strings?
And how many have you run into? Off the top of my head, I've seen--on the
MS-DOS/Windows platform the following: byte count+data, word count+data,
data terminated by 00, data terminated by 0a, data terminated by 0d, data
terminated by 1F, and probably a few others that don't occur to me right
I'm not a big fan of the "implement whatever weird nonstandard file
structure you like and hope no one loses the program that created it"
school of thought.
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