Unprotect 6/Unprotect-6.0.iso/update/airwrtim/fix116b.doc

Text File | 1994-12-31 | 7.5 KB | 140 lines

               FIX116B: Air Warrior Timing Patch V1.00
                Written by Bob Church  CIS:73207,3242

Background

FIX116B is a patching utility for SVGA Air Warrior V1.16B. It makes some
minor modifications to a timing loop in the joystick routine in the V1.16B
AIRWAR.EXE file to correct a problem which can occur with some game ports.
It was also found to be useful in the case of some problems with video sync
and lost key presses when Air Warrior is running at high frame rates.

The problem with the joystick is one caused by 'Refire Delay'. The routine
does not allow enough time between the reading of one axis and the next to
allow all game ports to reset correctly. This will happen on faster machines,
In the worst case, there will be a point on the Y axis (possibly on the
rudders and throttle as well), where as you move the stick from full forward
to full back, the joystick value as displayed by the 'ESC OJ1' command in Air
Warrior will suddenly drop off by 10 to 20 percent, maybe more. If you have
a throttle or hat switch, you may need to push them fully forward to observe
the effect. Try it both ways. It will happen at around the point where the Y
axis begins generating the highest value of the four joystick inputs as
reported on most any joystick test program. Lesser effects will generally
just be a 'jittery' response from the Y axis, perhaps the rudder, and the
throttle/hat inputs would be affected as well. The X axis would probably not
show any problems.

The problems with video seem to be related to high frame rates in AW. The
delay loop that FIX116B adjusts can be used to slow the frame rate down
slightly, and this has been found to be sufficient to bring the video into
sync on the system tested. It's worth a try if you're having that sort of
problem.

What the Patch Does

Basically, there is a loop at the end of the Air Warrior joystick routine
which waits for a fixed period of time or until the all four axes time out
before it goes on to read the next stick. The FIX116B patch makes two changes.
First, it forces the loop to time to conclusion, regardless of whether the
sticks time out first. This effectively inserts a minimum delay between time
out and refire which will stabilize the joystick reads. Second, it lets you
adjust how long the time delay will be, so you can tune it for the optimum
performance with your system. This delay can also be used to drop the frame
rate slightly, which appears to circumvent the video sync problems.

System Configurations

How you use FIX116B depends somewhat on how your system is configured. There
are two basic classes, I'll call them 'fully configured' and 'partially
configured'. A fully configured system is one which has something connected
to all four analog inputs on the game card. The system would typically have
a joystick, rudder pedals, and either an analog throttle or a ThrustMaster FCS
hat. If your system doesn't meet all these conditions, then it is partially
configured for the purpose of this discussion. Note that an FCS passed through
a WCS would provide a fully configured system (assuming you have rudder
pedals) if either the Red or the Black switch is in Analog Mode. If both
switches are digital, the system is partially configured.

Fully configured systems are the only ones that are likely to encounter any
of the problems mentioned above. The reason for this is that any open analog
input (which is the basic requirement for a partially configured system) will
cause the existing AW joystick routine to insert a delay of it's own while it
waits for the open axis to time out. This delay is generally more than enough
to circumvent the problem with refire.

Partially configured systems can use the patch to make some minor improvements
in frame rate by limiting the time that AW will wait for the open stick time
out. The value that AW uses in the unpatched timing loop is 2303, which is
longer than necessary for most systems, especially if an adjustable game card
is being used.

Using the Patch

First, if you are running a fully configured system and aren't experiencing
any problems, the patch won't really accomplish anything and will cause a
slight drop in frame rate. If your sticks and video are stable, then there's
nothing to be gained.

Using the patch is straightforward. You should make a copy of the AIRWAR.EXE
file in case something goes wrong. That is the only file that is actually
modified. Just put the FIX116B.EXE file in your Air Warrior directory and run
it with one of it's three command lines.

The first form of the command is simply:

                              FIX116B<enter>

This will patch AW with a loop value of 1279. This is a good place to start.
It will add about 6 milliseconds/frame on fully configured DX6 '66 and will
save about 6 milliseconds/frame on partially configured systems. The change
will be something less than that on faster machines. This should give plenty
of refire delay for the joystick, and was sufficient to fix the video sync
and keypress problem on the system for which the patch was developed.

The second form of the command is:

                            FIX116B nnnn<enter>

where 'nnnn' is a value between 1 and 65,535. This allows you to set the loop
value to something besides the 1279 default value. It is primarily useful for
tuning the value to match your system. Try the default first. If that clears
the problems, then try the second option and gradually lower the value. This
will get back some of the lost frame rate. You can keep pushing it down until
problems reappear. If you go to low, you will definitely run into joystick
problems at some point, probably when the joystick is back or right of center,
the right rudder is depressed, the hat is centered, or the throttle is at the
min throttle position.

If you have a copy of the ThrustMaster TMScope program, you can get an idea of
the minimum value necessary. Configure your system as it is for AW, including
your game card settings. Run TMScope and move all the flight controls through
their full range of travel. Take the highest 'Max' reading from the Raw Data
display and increase it by about 25%. That should be about optimum for the
delay value. If you have problems there, then go up with it until they go
away.

If the default value doesn't work, then increase the value above the default
and try again. I'm not sure how much delay it might take to correct the video
sync problem on all systems, so you'll just have to experiment a bit.

The optimum value for a particular system will change if you change game card
settings or your hardware configuration. If you are using a relatively high
value, like the default, this is usually not a problem. If you've tweaked the
value down, though, then changing things can cause problems to reaappear and
you will need to rerun the patch. You can run it as many times as you need to.
It isn't necessary to restore the original AIRWAR.EXE file each time.

The third option is:
                             FIX116B 0<enter>

Setting a 0 value is seen by FIX116B as a request to remove the patch from
the AIRWAR.EXE file and restore it to it's standard condition.


Distribution, Support, Etc.

I'm releasing this program for free use by anybody that wants to. You may
distribute it freely, post it wherever you like. If you have questions,
comments, bug reports, etc., you can reach me via email on Compuserve. My
ID is at the top of this file. Have fun!