Category : Alternate Operating Systems - Quarterdeck DesqView, CP/M, etc
Archive   : NOFF.ZIP
Filename : NOFF.DOC

NOFF.SHR

What is NOFF.SHR and why might I want to run it?

NOFF.SHR is a DESQview 2.X shared program that can be run with
some DESQview/TopView Aware programs which will improve the
performance of those programs (in DESQview, not in TopView).

To understand why this program might improve performance, it is
important to understand how a program that wants to be TopView
aware must write to the screen.

Essentially, such a program first makes a call to see if TopView
or DESQview is there. It then makes a call (we call it the "FE"
call) to find out the address in memory to write to. The program
then uses this address instead of writing to the hardware screen
address.

At this point, TopView and versions of DESQview prior to 2.0
diverge. TopView requires that the program make another call
(called the "FF" call) each time it wants to update the screen.
Used efficiently, this call can produce very fast screen updating
since it is possible to update only the portion of the screen
that has changed.

DESQview prior to version 2.0 however ignores the "FF" call and
takes on the task of determining when the screen must be updated
itself. This was done so that programs could be easily "DESQview
aware" without going to the trouble to be TopView aware. It is
quite efficient, although perhaps not as efficient as properly
using the "FF" call.

SO, WHY NOFF? Well, starting with DESQview version 2.0, DESQview
will detect the "FF" call, and if a program makes one, it will
not ignore the call, but will update the screen using the
"TopView" method. By supporting the "FF" call, DESQview 2.0 can
run some programs faster that previous versions of DESQview
could. An example are the DESQview Companions, all of which use
the "FF" call to advantage.

However, it has come to our attention that some DESQview/TopView
aware programs that use the "FF" call seem to use it rather
inefficiently, constantly updating the entire screen instead of
just the portion that changed. Since DESQview 2.0 pays attention
to the "FF" call and can't really make judgements as to whether
the call is used efficiently, these programs run slower in
DESQview 2.0 than in 1.XX.

LOADING NOFF.SHR
NOFF loads into your program window as a shared program (on the
Change a Program Advanced Options menu). Once loaded, it tells
DESQview to ignore the "FF" call even if it receives one. This
makes the programs update the screen faster and could eliminate
some screen abnormalities caused by improper implementation of
the "FF" call.

The following is a list of some DESQview Aware programs that seem
to benefit from NOFF.SHR and a few that work better without it.

SEEM TO BENEFIT FROM NOFF.SHR:

WordPerfect 4.1 } MUST install NOFF if you want to
WordPerfect 4.2 } run in 43 line EGA mode.

Norton Commander
Relay Gold and Silver
Watson

WORK BETTER WITHOUT NOFF.SHR:

All of the DESQview Companions
Crosstalk
LIST