On Sat, 8 Jan 2000, Martin Stark wrote:

> Hello friends,
> 
> `top` shows the following chart concerning memory consumption on my
> DECstation 2100/12MB RAM:
> 
> Memory: 3480K Act 792K Inact 380K Wired 920K Free 13M Swap 117M Swap
> free
> 
> Is that ok? And where is the rest of 12MB RAM?
> 
> I think I should be pointed to a sort of manual...
> 
> Greetings, Martin
> 

 I have wondered about this myself, I think it goes something like this:

Memory: 3480K and Free 13M doesn't mean what you think. On a Macintosh and
most non-UN*X platforms, each program grabs memory from the "whole" in
something called a shared memory tree. In that case, each program grabs a
set ammount of memory when they are started, they cannot be changed
without quiting the program and reloading it. In Windows and UNIces,
memory is not "grabbed", but heaped. Free 13M is the total amount of
memory the kernel is *currently* addressing, while Memory: 3480K is how
much of that memory is actually being used. Unlike the MacOS, the ammount
of memory being addressed changes on a need basis. The reason for
this: addressing all the RAM and VM space in your machine requires a
dedicated area of Physical RAM to store all the addresses and ranges
required to access the memory. So why address all the RAM and VM space in
your machine unless you need it? On my 5000/240 I have about 400MB of RAM
and no swap space. Believe me, if you start a kernel compile, the RAM will
go up in top. I've seen it as high as 24MB, but I don't sit and watch my
kernel compiles unless I'm inredibly bored :)

	Hope that makes things mildly clearer for you


Chris