From:	"A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk>
To:	DJGPP AT sun DOT soe DOT clarkson DOT edu
Date:	Fri, 15 Dec 1995 09:08:03 GMT
Subject:	The generation gap?

  (0) If a djgpp program calls a djgpp child process, will it always happen
successfully? What will happen if the parent is an old-style djgpp program and
the other is a V2 djgpp program? Or vice versa?
  (1) Of the various sorts and modes that programs djgpp and otherwise can be,
what pairs of parent mode and child mode are incompatible?
  (2) While the child is running, how much of the parent is in RAM rather than
swopped out onto disk?
  (3) I read that (except via files) a parent can only talk to a child via its
call parameters, and the child to the parent by the return value. Is there any
way that the parent can pass to the child a RAM address as a hex number, and
the child can thus poke and peek its parent's contents? Will it work if the
address thus passed across is the address of some conventional memory that the
parent had grabbed before by _go32_dpmi_allocate_dos_memory(&x)?
  (4) How much time overhead does calling a child, and returning from the
child back to the parent, use up?

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