To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: addressing real-mode (<1Meg) memory in djgcc?
Date: 	Fri, 8 Jul 1994 07:44:27 PDT
From: "Marty Leisner" <leisner AT sdsp DOT mc DOT xerox DOT com>


internal.doc says:
Mappings:

* First 1M mapped 1:1 to linear address 0x0000000
* Arena segments start at 0x10000000.  All utilities must be
  adjusted to reflect this by adding the constant ARENA to addresses.
* Symbol space is at 0xa000000 (used by debug32)
* Core (0-1M) remapped to 0xF0000000 (0xE0000000 to arena)
* VGA 256c paging at 0xE0000000 (0xD0000000 to arena)
    Three 1M pages:
      0xD0000000 - 0xD00FFFFF - read/write
      0xD0100000 - 0xD01FFFFF - read only
      0xD0200000 - 0xD02FFFFF - write only



There are also functions like 
	dosmemget()

which transfer data...

I'm somewhat confused (address *(0) is not 0:0 [or so it seems])

What does mapping mean?  (I assumed I could read the low memory directly,
but I can't...)



marty
Member of the League of Programming Freedom
leisner AT sdsp DOT mc DOT xerox DOT com  leisner AT eso DOT mc DOT xerox DOT com