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From: press@venice.SEDD.TRW.COM (Barry Press)
Newsgroups: comp.sys.ibm.pc
Subject: Re: How much memory is left during execution?
Message-ID: <54@venice.SEDD.TRW.COM>
Date: 9 Oct 89 15:54:25 GMT
References: <3178@tekcae.CAX.TEK.COM>
Reply-To: press@venice.sedd.trw.com (Barry Press)
Organization: TRW Systems Engineering & Development Division, Redondo Beach, CA
Lines: 5

It's really simple.  You issue a DOS call (I don't remember the one, offhand)
to allocate a memory block, and ask for 0xFFFF  paragraphs.  DOS will return
the number of paragraphs left (actually, the size of the largest block,
I think).  There's even a routine in the C runtime (_dos_???) to do the
allocation request.