Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!rutgers!njin!princeton!phoenix!jwbirdsa
From: jwbirdsa@phoenix.Princeton.EDU (James Webster Birdsall)
Newsgroups: comp.sys.ibm.pc
Subject: DOS memory allocation
Keywords: fooling with DOS's mind
Message-ID: <8261@phoenix.Princeton.EDU>
Date: 10 May 89 01:46:50 GMT
Organization: Princeton University, NJ
Lines: 30


   I need to be able to permanently allocate memory from a
memory-resident piece of code WHILE running an application without
fragmenting the memory when the application exits. It occurred to me
that an easy way to do this would to be allocate memory from the top
down instead of bottom up, as usual. Can DOS be persuaded to do this
in an elegant manner? If not, can it be kluged like so: if we need X
kbytes and there are N left, allocate a block of N-X, then the block of
X, then deallocate the first? Or would allocating from the top down also
count as fragmenting and cause DOS to vaporize?
   Assuming it can't be done, could I hook the exit interrupt and, when
it is called, call it and then somehow paw through the allocation chain
to find holes?

   Another random thought: I seem to recall hearing that DOS allocates
all available memory to .COM programs. Is this true? If it is, does it
spell certain doom for my plans?

   Yet another random thought: saw somebody praising the program MAPMEM
recently. I have version 2.1; I will admit that it's a nice program, but
sometimes using it causes some of my other memory mappers to scream that
the memory allocation chain has been corrupted! Don't know whether it's
MAPMEM's fault or not.

   Anyway, thanx for any thoughts on the questions above...

-- 
James W. Birdsall  jwbirdsa@phoenix.Princeton.EDU  jwbirdsa@pucc.BITNET
   ...allegra!princeton!phoenix!jwbirdsa   Compu$erve: 71261,1731
"For it is the doom of men that they forget." -- Merlin