From:	"Tony O'Bryan" <aho450s AT nic DOT smsu DOT edu>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Physical Memory
Date:	Tue, 06 Jan 1998 14:05:41 -0600
Organization:	Southwest Missouri State University
Lines:	65
Message-ID:	<34B28E95.2D92@nic.smsu.edu>
References:	<19980106192149 DOT 8027 DOT qmail AT hotmail DOT com>
Reply-To:	aho450s AT nic DOT smsu DOT edu
NNTP-Posting-Host:	marie.a30.smsu.edu
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

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John Patton wrote:
> 
> Hi,
> 
> I am trying to locate some code that gets the
> amount of actual physical memory installed on
> the machine.  I am not concerned at this time
> about virtual memory or available memory.  If
> the machine has 32MB of real memory, I want to
> display this.  I tried using the biosmemory()
> function and the most I can get it to return is
> 640k.  My machine has 32MB installed, not 640k.
> If anyone knows a way to do this, I would greatly
> appreciate it.

This polls the CMOS to determine how much memory your system has:

-- 
Tony O'Bryan

http://www.geocities.com/SiliconValley/Park/7201

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#include <stdio.h>
#include <dos.h>

int GetPhysicalMemory(void)
  {
  unsigned BaseMemory;
  unsigned ExtendedMemory;

  /* Gets the amount of base memory from CMOS up to 640K */
  outportb(0x70,0x15);
  BaseMemory = inportb(0x71);
  outportb(0x70,0x16);
  BaseMemory += inportb(0x71) << 8;

  /* Gets the amount of extended memory from CMOS */
  outportb(0x70,0x17);
  ExtendedMemory = inportb(0x71);
  outportb(0x70,0x18);
  ExtendedMemory += inportb(0x71) << 8;

  /*
   * Always leaves off the 384K between 640K and 1M, so add it in if there is
   * any extended memory present.
   */
  ExtendedMemory += ExtendedMemory ? 384 : 0;

  return ExtendedMemory + BaseMemory;
  }


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