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
> scenario?
>
> 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.

Warner

>