C-kermit fails

[Paul Eggert]

On 7/31/20 11:22 AM, Frank da Cruz wrote:
> Software development was not like
> this when computing was dominated by companies like IBM and DEC, who were
> dedicated to preserving their customers' investments in software because if
> they didn't, they'd lose those customers.

That wasn't my experience at all. IBM and DEC regularly broke user applications 
and said the equivalent of "If you don't like it, then just keep running the old 
OS on the old hardware." They then tried to sell you new stuff, and if you 
refused they eventually stopped supporting the old stuff.

For example, circa 1978 if you wanted to use a PDP-11/70 and selected DEC's 
operating system RSTS, you would have been kinda out of luck by around 1983 when 
the PDP-11/70 was obsolete. DEC told customers to switch to VAX/VMS, and gave 
some upgrade paths (late-1970s VAX hardware would emulate PDP-11s and if you 
threw DEC some more money VMS would support RSTS user processes, albeit 
inefficiently) but DEC dropped those upgrade paths in later VAX hardware and you 
were stuck. The last RSTS release was in 1992 and DEC stopped supporting RSTS 
soon after.

Had you selected Unix instead in 1978, you'd have been golden. Your software 
would still run today, with only minor changes. I still run some personal 
Unix-based software now that I originally ran on a PDP-11 in the late 1970s.

And it wasn't just DEC. I remember the FAA using IBM mainframes in their air 
traffic control systems designed in the 1960s and written in 360 assembler with 
CCW programs. The FAA kept running this stuff on an old IBM OS on old IBM 
hardware until IBM told them around 1980 that IBM wouldn't support it any more. 
IBM then sold the FAA on a replacement system called AAS that cost billions and 
never worked. See 
<https://www.sebokwiki.org/wiki/Federal_Aviation_Administration_(FAA)_Advanced_Automation_System_(AAS)> 
for some of this sad history.

Although I'm sure one can cite examples of old-time backward compatibility, I'm 
exceedingly skeptical that the old days were any better than now overall in that 
department. Quite the contrary. In particular, the GNU C library is *much* 
better about backward compatibility than IBM and DEC were in the "good old days".