Newsgroups: comp.unix.sysv386
Path: utzoo!telly!evan
From: evan@telly.on.ca (Evan Leibovitch)
Subject: Re: Looking for i386 versions that support >16Meg memory
Organization: Somewhere just far enough out of Toronto
Date: Sat, 10 Nov 90 15:07:16 GMT
Message-ID: <273C17A5.2621@telly.on.ca>
Keywords: i386 OS
References: <728@bulus3.BMA.COM>

In article <728@bulus3.BMA.COM>, haugen@bulus3.BMA.COM (John M. Haugen) writes:
> I know Interactive Unix does not support more than 16 megabytes of memory.
> Would there be other versions of Sys V based Unix that support more than
> 16 megabytes of memory?
> 
> Does SCO, Everex, Intel, and the others also have this limit??

I recently installed Esix on two 486 EISA systems with 24 Meg each.

At the start, the bootup BIOS showed that the hardware saw 24
Meg, but the ESIX bootup said it only recognized 16 of it.

The first thing to check is the MEMRANGE value in /etc/default/boot.
In my case, this alone did not help.

Then, after asking around, I was told (tho' I'm not sure how true it is)
that the original IBM spec for the old AT architecture did not deal with
extended memory beyond 16 Meg. Therefore, there were technically ways in
which manufacturers could play with that area without breaking the spec.

So, the official line, as I understand it from both Interactive and Esix
(and maybe others) is that "386 Unix *should* recognize normal extended
memory beyond 16 Meg, but we won't support it because some manufacturers
may implement that memory in strange ways."

Indeed, after finding nothing in Unix that would get it to recognize
beyond 16 Meg, I checked the box's hardware manual. The box had come
shipped with hardware caching and "Shadow RAM" enabled - disabling both
allowed the Esix to boot and recognize the entire 24 Meg.

Not supported, maybe, but it worked! 

-- 
Evan Leibovitch, Sound Software, located in beautiful Brampton, Ontario
    evan@telly.on.ca / uunet!attcan!telly!evan / (416) 452-0504
           ...quoth the Raven, "Eat My Shorts!" -- Bart