[TUHS] screen editors / machine load

[Mary Ann Horton]

Yes, it was a real concern. Physical memory on the shared PDP-11 was 
limited, and if everyone had a separate copy of vi running the machine 
would swap itself silly.

This only mattered if everyone had their own separate copy of vi 
installed. The fix was to put vi in a single system directory, such as 
/usr/ucb or /exptools. The instruction part of its memory would be 
shared among all the users, resulting in much less swapping.

In the early days, people tended to have their own personal copy because 
the Berkeley tools did not come standard with UNIX, especially at Bell 
Labs. That was one of the main motivations for Exptools (the 
"experimental tools"), which were basically 2BSD's applications and some 
other tools like Warren Montgomery's emacs. Disk space and people's time 
spend installing were also good reasons.

     Mary Ann

On 1/10/20 5:41 AM, Mike Markowski wrote:
> seeing him fire up vi was practically sci-fi to me.  He showed me a 
> few commands and vowed me to secrecy for fear if all students started 
> using it, it would bring the 11/70 to its knees.  Were multiple vi 
> sessions really such a potential burden to the machine?  I wouldn't 
> think so with the slow nature of human i/o, yet there certainly were 
> times when the pdp-11/70 crashed as project due dates loomed closer 
> and closer!