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Mail Archives: opendos/1997/04/17/14:28:44

From: "Matthias Paul" <MPAUL AT ibh DOT rwth-aachen DOT de>
Organization: IBH, RWTH-Aachen
To: opendos-developer AT delorie DOT com
Date: Thu, 17 Apr 1997 20:20:52 GMT+0100
Subject: Re: Usage of directory entries
Reply-to: Matthias DOT Paul AT post DOT rwth-aachen DOT de
Message-ID: <1404FA328C0@ibh.rwth-aachen.de>

On Thu, 17 Apr 1997, Mark Habersack wrote:

> > There is also some weird way that DBLSPACE/DRVSPACE have some weird scheme
> > working as an installable filesystem, I don't really know how stacker does
> > it (although I assume it's similar)
> They use some tricks to inject their code into the system (remember the 
> DRVSPACE.BIN file?) and work as a replacement for the FS/DEVICE FAT 
> routines built into the kernel. Stacker probably uses the 
> DRIVER.SYS approach (I'm not sure).

STACKER (at least since 3.10+) also uses the so called pre-load API in 
IBMBIO.COM (before execution of CONFIG.SYS).  This has been a major 
law act at that time, when Stac sued Microsoft for using Stac patented
algorithms in DBLSPACE without licensing them, and Microsoft was 
forced to stop shipping MS-DOS 6.20 (including DBLSPACE) and replace 
it by MS-DOS 6.21 (without DBLSPACE).  However, Microsoft had a longer 
breath and sued Stac for de-assembling the undocumented pre-load API 
in MS-DOS 6.20+ (needed to let STACKER install the same way as 
DBLSPACE could).  Since Stac suffered from M$ pressure and was almost 
running out of money, they made a deal with M$:  Stac was 'allowed' 
to use the pre-load API (as also de-assembled by many other vendors 
without being sued for), and M$ could ship DRVSPACE with MS-DOS 
6.22...

 Matthias

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