Starting back in OS/360 days, user modifications utilized the sequence number to indicate where to apply the various multiple user modifications against the base operating system source code. I know our site was still using JES2 user modifications until about 4 years ago. This has mostly been supplemented by exit routines.
Outside mainframe operating systems, most user customization is done by writing your own program instead of modifying the base operating system. And programs come as complete units instead of merging multiple user modifications. On Tue, May 3, 2011 at 9:35 AM, Paul Gilmartin <[email protected]> wrote: > On Tue, 3 May 2011 09:03:12 -0500, John McKown wrote: > >>Then explain them to this poor fool. I find them to be a useless >>anachronism. And your answers tend to be so short as to be unhelpful. >> > PACK, surely. Nowadays, that function is best left to microcode > in the DASD subsystem so it can be transparent to all applications. > (Unless you consider CPU cycles cheaper than I/O bandwidth.) > >>On May 3, 2011 8:03 AM, "Shmuel Metz (Seymour J.)" wrote: >> >>>And, yes, I know about ISPF's "modification level" use of the >>>sequence columns. >>Suggesting that you don't understand the issues. The use of columns >>79-90 is only a minor part of why sequence numbers are useful. >> > I've long wondered, if sequence numbers are so valuable, why > haven't they spread outside the progeny of unit record systems? > > o Well, there's COBOL, which allows sequence numbers at both > left and right ends of the line. > > o And BASIC, or at least used to be. Does Microsoft VBA still > use sequence numbers for editing? And have a RENUMBER > command wihch updates GOTOs accordingly? > > o A colleague once described to me an [S|X]DS Sigma system which > stored text files as a sort of KSDS (no, not the San Diego > radio station). The keys were the sequence numbers, and > mandatory. I suppose this allowed efficient insertion or > deletion of lines. > > o PDP-6 et seq. stored 5 USASCII characters in a 36-bit word. > If the sign bit was set in the first word in a line, that > word was treated as a sequence number (but by what translators > or applications?) > > Most of these conventions are obsolescent. > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: GET IBM-MAIN INFO > Search the archives at http://bama.ua.edu/archives/ibm-main.html > -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
