From: "Rodney W. Grimes" <rgrimes AT gndrsh DOT cdrom DOT com>
Subject: Re: Accessing real memory (ie, below 1MB) under go32
To: sandmann AT clio DOT rice DOT edu (Charles W. Sandmann)
Date: Tue, 14 Sep 1993 17:20:58 -0700 (PDT)
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu, dj AT ctron DOT com

> 
> > The dosmem.s file allows you to read and write memory below 1M.  What
> > they don't provide is a mechanism for allocating and freeing memory
> > below 1M.  These functions are currently useful for accessing the BIOS
> > data area or at-bus peripherals.
> 
> There is a 4K buffer in low memory (___transfer_buffer contains the 
> 32 bit address in .s gas code).  This value is currently only set for non-DPMI
> mode (and is NULL for DPMI).  This area can be used if you understand the
> GO32 extender calls which use it and don't interfere with them.
> 
> If you are willing to do DPMI only, you can call the Int 31h call to allocate
> low memory under DPMI.  This is probably better, since I believe V1.11
> emulates this DPMI function for non-DPMI, so you would have future
> compatibility built in (is this correct DJ?)
> 
> Finally, I know that for one commercial software project that has
> been recently done with DJGPP they needed to add Int 13 support to the
> extender.  Maybe it's time to put that in the release?

Can you point me to these folks please, I really don't like to reinvent
the wheel.  This is the one piece that is holding me up at this time,
and I am hacking on it, but it will take me some time to get it all
working. 

> I missed part of the discussion, our mail area has been full for the last
> week so I didn't get any mailing list items :-(

Basically I need to do int 13 I/O from a go32 program.  I am writting
install tools for FreeBSD that run under DOS (fdisk, disklabel, and a
very special tar that can extract tar files into a ufs formatted file
system on harddisk).


-- 
Rod Grimes						     rgrimes AT cdrom DOT com