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From: rml@hpfcla.UUCP
Newsgroups: net.micro.hp
Subject: Re: Access to HP9836U
Message-ID: <152200002@hpfcls.UUCP>
Date: Mon, 10-Feb-86 18:13:00 EST
Article-I.D.: hpfcls.152200002
Posted: Mon Feb 10 18:13:00 1986
Date-Received: Sat, 15-Feb-86 03:04:44 EST
References: <612@puff.UUCP>
Organization: 10 Feb 86 16:13:00 MST
Lines: 19

> Does anyone know of a way to access the HP9836U graphics memory using
> assembly? According to the manual, the memory resides from $530000 - $53xxxx.
> The problem that I had was that the O/S wouldnt let anything reference outside
> a predetermined address boundary.

Those addresses are physical addresses.  They are not mapped into the
address space of user processes in HP-UX.  The 5.1 release of HP-UX will
include a driver (graphics(4)) which does just that.  It is possible
(but slow, and probably not useful) to access those addresses through
/dev/mem.  If you don't need UNIX/HP-UX, the Pascal Workstation system
allows access of physical addresses.

> I tried to set the 68000 supervisor mode on but that didnt seem to be working

It's an important feature of the intruction set of any machine that code
running in one protection mode cannot increase its privileges.

			Bob Lenk
			{hplabs, ihnp4}!hpfcla!rml