*BSD News Article 5413


Return to BSD News archive

Path: sserve!manuel!munnari.oz.au!spool.mu.edu!agate!soda.berkeley.edu!wjolitz
From: wjolitz@soda.berkeley.edu (William F. Jolitz)
Newsgroups: comp.unix.bsd
Subject: Re: [386BSD] RAM > 16MB OK ?
Date: 22 Sep 1992 17:36:47 GMT
Organization: U.C. Berkeley, CS Undergraduate Association
Lines: 21
Distribution: world
Message-ID: <19nljfINNksv@agate.berkeley.edu>
References: <19krluINNd2l@corax.udac.uu.se>
NNTP-Posting-Host: soda.berkeley.edu


In article <19krluINNd2l@corax.udac.uu.se> goran@astro.uu.se (Goran Hammarback) writes:
>I know there was a discussion on SYS V UNIX for the PC, where the
>conclusion was that most of these systems only handled up to 16 MB
>of ram, the reason being that the ISA bus can only access the first
>16 MB of memory.  Does anyone know if 386BSD handles more than
>16 MB ? (The obvious solution would be to use a buffer in the lower
>16 MB for transfers to/from higher memory).

We have a 20MB system working in-house. The idea is that you copy portions of
memory on-the-fly to the "lower" physical 24-bit address. 

BTW, even if you have an EISA-bus machine with 32-bit address ISA compatibility,
it still means you can only get to the lower 24-bits of physical address.
This is why one wants to get a native mode EISA disk controller that does
the full 32-bit address space, like an Adaptec 1742 or Bustek 742.

0.1 works without changes (Bill threw it in 2 hours before the tape was
cut), but there is always more testing and work to do.

Lynne.