🚀 go-pugleaf

In article <1992Sep1.160133.19060@mits.mdata.fi> kennu@mits.mdata.fi (Kenneth Falck) writes:
>
>So, the question remains, why don't the Microsoft programmers bang
>their brains together and rewrite MSDOS to be fully re-entrant and
>all the routines to use dynamic memory allocation instead of static?
>
>If this really is so difficult for them, I must have understood
>something wrong about this.
>


Because some of the data is naturally not sharable between routines
which can interrupt each other.  Consider the FAT (allocation table)
for a disk.  You don't want a routine to start allocating a new disk
sector for a file, and have it interrupted by another routine which
allocates the same sector.

Now, you can put software locks around critical data structures to
avoid this, but it's a lot of work to add this to a system and it
won't buy you much in DOS.  In a system that supports multi-processing,
it's a requirement, and all such systems do it.  You won't find it
added to DOS until it supports multi-processing.  That's what NT is
all about (that, and real 32-bit software).


-- 
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=			Jeff Kenton	(617) 894-4508			=
=			    jkenton@world.std.com			=
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