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c++.dos.16-bits - How to make my 16-bit app 'play nice' under XP?


I am developing a 16-bit DOS helper application that works with a 32-bit
Windows console application.  The function of the 16-bit app is to access
emulated features of ntvdm that 32-bit console apps (so far as I can tell) do
not have access to, specifically blinking text and full-screen 40-column text
mode.  The 32-bit console app does the network communication required that
16-bit DOS programs (so far as I can tell) do not have access to under NTVDM.
 While the 16-bit helper program works fine, it has a busywaiting problem.
While waiting for instructions from the 32-bit console app, it uses >95% CPU.
 There are several documented interrupts for DOS programs to call when they
are idle, but none of them seem to do the trick to tell WINXP that the program
is idle.  I've tried INT 28h and Int 2Fh function 16h subfuction 80h.  Neither
reduces the CPU usage of my program.  Any ideas?
Apr 09 2012