All-Ram System possible?

[H. Apfel]

I will try and use an old Mac as control system for my new home, i.e. 
it should manage heating, warm water and aircon. Obviously I'll need 
a stable system with low failure rate. So I thought about a OS which 
may boot from a ROM or HD, but which will reside in and use only ram, 
from some log files.

So how much memory yellow dog really needs for, say, the kernel, some 
drivers (HD, ethernet, USB-Stick), Konqueror and a self-written app 
in C (a no-memory-hog) ? Would it be possible to run it from a iBook 
G3-500 (384 MB ram)?

Thanks for the answers

Holger