From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Mon,  7 Feb 1994 20:08:44 -0500
From: forsyth@minster.york.ac.uk forsyth@minster.york.ac.uk
Subject: memory
Topicbox-Message-UUID: fffdddb8-eac7-11e9-9e20-41e7f4b1d025
Message-ID: <19940208010844.IffFVN3K0Y4DAYeMJddeCQp8qSlxCD2qeiwEQbfKNuE@z>

>>	8-16 megs should be adequate.  More is better.

it depends on what you are doing.  on a standalone machine
at home, i have 32 Mb but rarely use more than 5 Mbytes, if that.
you need 8-12 Mbytes to link the pc cpu/terminal kernels quickly.
i've linked one on a 4 Mbyte 386sx16, but it takes a long time
with much paging.

on a shared CPU server, or especially a file server, more is better.
the catch is that on an ISA bus machine, you can't DMA above 16 Mbytes,
so the system must copy the data below 16 Mbytes & DMA from there.

at work, i use a 4 Mb 386sx16 as a terminal, which runs 8-1/2 but
i run cpu in most windows (except sam -r and seemail).
note that unlike most X11 implementations, the editing in each window
including mouse handling is done locally, so i'm not affected by load
on the network or CPU server.

i currently run special-purpose CPU servers (DNS servers, ftp servers)
on lots of things that haven't got a lot of memory.
for instance, a DNS service runs happily on a 386sx16 with 4 Mbytes
running a pc cpu kernel.  (in case you wondered, we have a lot of 386sx16
4Mbyte machines about the place.)
i am planning to upgrade the CPU on that, but i'll keep it with 4 Mbytes --
that's plenty.

on a PC, if you are going to use /dev/bitblt, you have to allow some extra
space for the shadow copy of the screen.  it's a modest amount at 1 bit-per-pixel,
but rather more for 8-bit colour.
perhaps one day, with PCI, some of this waste will go away.

anyhow, i didn't want anyone to get the wrong idea: plan 9 runs very well
on configurations that SunOS, Solaris, Windows/NT and even OS/2 would disdain.
remember that you can take advantage of the ease of distribution that
the system gives you.