Subject: Re: "Extended" memory?

From: Mr Stuart Lamble <[email-masked]>
Date: Mon, 26 Aug 1996 12:46:41 +1000 (EST)

In article <[email-masked]> bhaskar wrote:
: I see that the Debian installation instructions contain the following.
: >Extended vs. Expanded Memory
: >If your system provides both extended and expanded memory, set it
: >so that there is as much extended and as little expanded memory
: >as possible. Linux requires extended memory and can not use
: >expanded memory.
: 
: I'm confused, since unices make no such distinctions between memory.
: This is under the BIOS settings instructions, so presumably there
: were systems where the BIOS somehow configured the memory to behave
: like extended memory?

Indeed. As an example, at home I have a 486, and two 286 class systems.
One of the 286 machines is based around the NEAT chipset, which allows
you to do all sorts of neat stuff (pun not intended, but I'll keep it
there anyway. :-) It has 4MB of RAM, 2MB of which is earmarked for EMS;
the rest is the base/extended. Changing the size of the EMS block is
trivial - just modify the CMOS settings, and reboot.

Linux switches into 386 enhanced mode, which treats memory as one big
continuous block. _However_, this only works if the memory is set up
to work as extended memory. EMS was designed to get around the 640KB
limit on 8086, 8088, and 80186-based systems. (yes, there _was_ an
80186 chip; it just wasn't widely used in the same way that the 8088,
80286, 80386, and 80486 were.) [yes, I know, it's the i486...sheesh.
I was on a roll there. :-) ]

Basically, the simple answer is that you can "see", and use, extended
memory in 386 enhanced mode, which Linux runs under. You cannot "see"
expanded memory, making it useless under Linux.

-- 
Windows is not the answer. Windows is the question. Linux is the answer.
http://sunsite.unc.edu/mdw/ for all your PC software requirements.

---

From: Mark Eichin <[email-masked]>
Date: 30 Aug 1996 16:41:18 -0400

> 80286, 80386, and 80486 were.) ...

Actually, the 186 is probably *more* used than the others, just not
in home-user pc's:
	* many X terminals used the 80186 as network/keyboard controller
	* the HP95/100/200 LX handhelds use a cmos 80186
	* the AT&T ISDN phones have an 80186 in them

Needless to say, linux doesn't run in any of these environments
(though I suppose ELKS would, I don't know how far along that is...)