🚀 go-pugleaf

elhadad@cs.columbia.edu (Michael Elhadad) writes:

>I'm trying to understand when and why to use GlobalDosAlloc as opposed to
>GlobalAlloc.  Assume I am running in enhanced mode.  The only difference I 
>have read in the doc is GloabalDosAlloc will allocate the memory under the 
>1M line.  Why should that make a difference to an application?

Hi!

There are two cases I can think of, where GlobalDosAlloc() would be prefer-
able to GlobalAlloc() :
   - For data items, pointer to which is passed to certain INT calls, some of
     which run in real mode, and can therefore use the bottom 1M only
   - For co-operationg DOS/Windows apps, which would communicate thru common
     memory, that's addressable by both

Related Q:
There's also function GlobalWire() , which is somewhat 'stronger' way to lock
a memory block.  Its documentation says, that the block is first moved to a
lower address before locking.  The handle received seems to be usable in an
interrupt server running in a 286 system (standard mode).  I'm in doubt of
whether this implies, that the block is *always* moved all the way down to
the first 1 meg, failing in case of no free space there (as opposed to using
a higher address instead). Any way to check, ie. to allocate all of the *DOS*
memory, but none other (a'la GlobalAlloc(-1) or GlobalCompact() )?

Today's slogan:
"There are three kinds of memory in an XT: Extended, Expanded and Exhausted."
   - R.L.

Terveisin: Risto Lankinen
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