Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!voder!nsc!taux01!amos
From: amos@taux01.UUCP (Amos Shapir)
Newsgroups: comp.sys.nsc.32k
Subject: Re: Mod Table
Message-ID: <1814@taux01.UUCP>
Date: 6 Jun 89 05:12:02 GMT
References: <507@trwrc.UUCP>
Organization: National Semiconductor (IC) Ltd, Israel Home of the 32532
Lines: 21
Hdate: 3 Sivan 5749

The mod table is anywhere the mod register points to; that means that
each user can have as many tables as s/he likes; only one of them is
active at any given time.

The table has to be located in the lower 64Kb of memory, but that
address is virtual; if a MMU is used, the address would be translated it
to its proper physical location.  The statement in the Grey Book (about
the table being located in the first 64Kb of physical memory, and mapped
to virtual address 0 in user space) is misleading - that's the way this
is currently done in most implementations of UNIX, but this scheme is
not dictated by hardware.

Finally, on a 32532 in Direct Exception mode, the mod table can be
completely ignored.


-- 
	Amos Shapir				amos@nsc.com
National Semiconductor (Israel) P.O.B. 3007, Herzlia 46104, Israel
Tel. +972 52 522261  TWX: 33691, fax: +972-52-558322
34 48 E / 32 10 N			(My other cpu is a NS32532)