Path: utzoo!attcan!uunet!jarthur!elroy.jpl.nasa.gov!swrinde!zaphod.mps.ohio-state.edu!rpi!uupsi!sunic!kth.se!cyklop.nada.kth.se!news
From: d88-jwa@byse.nada.kth.se (Jon W{tte)
Newsgroups: comp.unix.aux
Subject: Re: Tops compatibility with A/UX
Message-ID: <1991Feb27.114401.20741@nada.kth.se>
Date: 27 Feb 91 11:44:01 GMT
References: <18243@slice.ooc.uva.nl>
Organization: Royal Institute of Technology, Stockholm, Sweden
Lines: 33

In article <> morgan@ooc.uva.nl (Chris Morgan/RIKS) writes:

>another 4x4MB simms which I hope to see in about 2-3 weeks. Until then, is it
>possible to take advantage of the virtual memory capabilities of the IIfx,
>which I fully expect exist ???  Currntly the machine is pretty slow with a
>hell of a lot of disk activity. When I try to run MacX or X11...

>practical even for a IIfx. Surely it must be possible to trick A/UX into
>thinking that theres more memory available than is physically installed.

Erhm... Think about it.

Q: Right, the computer thinks it has more memory. Now, where would it
    actually _put_ the data that goes into that memory ?

A: On the disk.

Q: What's all your disk activity when running X ?

A: Paging (and most probably swapping) because of your tiny physical
   memory.

UNIX Sys V (which A/UX is) has support for virtual memory and
uses it both for paging and for swapping. The whole _point_ of
virtual memory is to emulate memory using disk... as you clearly
see evidence of, it works, but it's slow on heavy usage. That's
why computers don't come with 1 MB RAM and the rest as "virtual" :-)

							Jon W{tte

"The IM-IV file manager chapter documents zillions of calls, all of which
seem to do almost the same thing and none of which seem to do what I want
them to do."  --  Juri Munkki in comp.sys.mac.programmer