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From: herder@myab.se (Jan Herder)
Newsgroups: comp.sys.nsc.32k
Subject: Re: Mod Table
Keywords: NS32k ModTable
Message-ID: <466@myab.se>
Date: 7 Jun 89 13:07:39 GMT
References: <507@trwrc.UUCP>
Reply-To: herder@myab.UUCP (Jan Herder)
Organization: Myab Gothenburg, Sweden
Lines: 24

In article <507@trwrc.UUCP> agnew@trwrc.UUCP (Robert A. Agnew) writes:
>The National programmer's manual for the 32k says that the module table
>must exist in the first 64k of physical memory. The Texas Instrument
>(second source) programmer's manual for the 32032 states that there can
>be 64k of module table per user.  These statements appear to be
>inconsistent. What happens in supervisor mode? Does the super have his
>own module table?  Anyone know the truth on this matter?

    The problem is that pointer to the module table is a 16 bit register.
This means that the module table must be in the first 64K of memory. 
There must be a module table in first 64K of physical memory, since the
virtual memory is not enabled after reset. Once the virtual memory is enabled
it's possible to have it anywhere in the physical memory, even for the super-
visor state, which has it's own module table. 

    Note that the module table is a leftover from the days when Pascal
was the model. It's not used in UNIX V.3 on ns32000, except for the
interrupts. And that's because you must use it there. 

-- 
Jan Herder, MYAB Sweden                    |  Phone: +46 31 18 75 12
Internet: herder@myab.se                   |  Fax:   +46 31 18 28 42
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