On Thu, Dec 23, 2021, 8:54 AM Dr Iain Maoileoin <iain@csp-partnership.co.uk> wrote:
On 12/23/21 2:19 PM, Larry McVoy wrote:
On Thu, Dec 23, 2021 at 01:05:55PM +0000, Michael Kj??rling wrote:
On 22 Dec 2021 18:18 -0800, from lm@mcvoy.com (Larry McVoy):
The CP/M machines bring back different memories, using that and BDS
C because an 11/780 with 4MB of ram and 40 users meant each user was
getting 1KB so it swapped and swapped and swapped.
4 MB RAM and 40 users works out to 100 KB of RAM per user for me. Even
accounting for a large at the time OS it should be several tens of
kilobytes per user on average for actual useful data. So, because
there's probably some detail here that means you're right and I'm
wrong, how do you arrive at the figure 1 KB of RAM per user in that
Probably boomer doing math wrong. 

I might get flamed for this comment, but is a number divided by a number not arithmetic.  I cant see any maths in there.

In my support I point out that the "dc" manual page says

 dc  is a reverse-polish desk calculator which supports unlimited precision arithmetic.

In Scotland - at least years ago - arithmetic was an examinable subject at the lower grades (you also get a mathematics exam at the same grade).

Arithmetic could not be taken past the basic level, mathematics could.

Nowadays they have lumped arithmetic into maths (pronounced "maffs").

Do other countries have this change in language?

Sorry for the intrusion. It is Christmas with me (or is it "happy holiday" to be politically correct).

 You are right, I'm wrong.  Though I
will say that 100K/student was _painful_.  Not enough to run make/cc in
any reasonable time.  About the only thing that worked was ^t (I think
that was it) that showed you some basic info about performance.
I had forgotten about control-t - does anything modern still do that

FreeBSD does. It's my biggest annoyance with Linux that it doesn't.

100k for a process that likely needed 500k to 1MB would indeed be swapping its brains out. So while tha vax could do I/O 10 times faster than a Z80 of the era and run maybe 5 times faster, all that was lost when you started thrashing because you can't keep your working set in memory.