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From: kneller@ucsfcgl.UUCP (Don Kneller%Langridge)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS Windows and Physical memory?
Message-ID: <9965@cgl.ucsf.edu.ucsfcgl.UUCP>
Date: Thu, 11-Dec-86 16:35:21 EST
Article-I.D.: cgl.9965
Posted: Thu Dec 11 16:35:21 1986
Date-Received: Sat, 13-Dec-86 22:23:20 EST
References: <105500001@datacube>
Reply-To: kneller@cgl.ucsf.edu.UUCP (Don Kneller)
Organization: Computer Graphics Laboratory, UCSF
Lines: 24

In article <105500001@datacube> berger@datacube.UUCP writes:
>
>Has anyone had experience using Microsoft Windows where they need
>to talk to hardware using pointers?  Does Windows allow explicet
>pointers to physical memory?
>
>For example
>
>char *p;
>
>	p = 0xa0000; /* Set p to point to some hardware location */
>
>	*p = 0xff;	/* Set the register to some value */

I don't know about Windows, but this may not work because pointers may
not be stored in the same format as longs.  For Microsoft C, the above
*won't* work.  I assume your trying to reference segment A000, offset 0.
In MSC you would say FP_SEG(p) = 0xA000; FP_OFF(p) = 0x0;  This is
definitely not the same as p = 0xA0000.
-- 
	Don Kneller
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