1 Mar
2026
1 Mar
'26
4:26 p.m.
On Mar 1, 2026, at 5:23 PM, Jay Jaeger via cctalk
<cctalk(a)classiccmp.org> wrote:
...
Having not used the CDC operating systems, I can't speak knowledgeably to them, but
still, I can't imagine the master being on actual cards. Way too hard to manage
changes.
I don't know about the earliest days. But when I worked with CDC NOS around 1975,
everything (OS and applications) was handled by one of two rather similar source control
systems, MODIFY and UPDATE. These would maintain a "program library" file,
consisting of "decks" (individual programs), and you would feed them a control
deck identifying which deck(s) you wanted to extract and/or change. For example, to
assemble a program you'd run MODIFY to obtain a text file containing the deck of that
program, or possibly several decks if the program was handled that way. That file would
then be fed into the assembler.
That intermediate file had a compression scheme where spaces were run-length encoded,
similar to the IBM approach that was just mentioned. At CERL, there was support for text
files encoded that way, which were known as "squoze" files. Over time that
faded away, I'm not quite sure why.
UPDATE was basically the same. I never understood why there were two; perhaps a legacy of
the two main OS streams: MACE/KRONOS/NOS and SCOPE/NOS-BE. The only UPDATE PL I ever ran
into was for the 7054 (RP04-like) disk controller firmware.
paul