VROOM is their overlay manager.  That is, it allows you to write programs
which execute in a conventional DOS memory (aka 640K) which is smaller
than the size of the compiled program.  For example, on a machine with
550K available conventional DOS memory, you can run a program 1Mb large.

I've written a number of apps using it.

Benefits:
1) It does what it claims: big programs run on small machines.

2) Because it uses conventional DOS memory and interrupts, almost any
existing, working, DOS code can be re-compiled into an overlaid program.

Drawbacks:
1) The resulting programs are slow.  The programs swap executing program
code to and from disk.
2) Compiling overlaid programs can be messy.  Complex C++ class
hierarchies and very large programs cause compiler and linker problems.
3) Third party libraries are impossible to include in overlaid programs
if you don't have the source code, and troublesome to include even if you do.

Alternatives:
1) Write programs that use extended memory.  Borland has *finally* decided
to include 16-bit and 32-bit extended memory programming with their
compilers (they sell it as their "Powerpack").  The other PC compiler
vendors also sell extenders, or are compatible with Phar-Lap, etc.
2) Use other techniques: multiple small programs, etc.


I've converted all of my VROOM (overlaid) programs to use extended memory.
Vroom was nice while I needed it, but I'm *really* glad I don't need it
any more.

(Save your breaths, Unix programmers to whom this discussion seems like
lunacy.  We know, we know...)

Final note:
Don't use VROOM if you don't have to: in a couple years, the need to
write applications for conventional DOS memory should disappear.

Hi!
I very need information about usage VROOM
in the Borland Turbo C++ or Borland C++.
Thanks.
  Alex.