[DMDX] Re: Timing with a USB gamepad At 08:37 AM 6/9/2005 -0700, you wrote:

>   I would hope it's SD would be below 1ms.  I'll know some time today as 
> one of my techs will have brought in a USB game pad from her home.

   Here's what I've added to the Input help after testing the gamepad:

     It turns out that the above USB mouse times are bad not necessarily 
because of the mouse per se but more because XP only polls USB devices at 
125Hz.  There are various hacks around the internet that can change that 
polling rate for gamers so I decided to revisit the USB issue and see if 
the USB Mouserate Switcher has any effect.  Times are for testmode 8 on a 
USB Logitech Trackman:

XP SP2 P4 2.4 GHz, USB mouse, no rate modifications (qPIO12 still active, 
oops) 8 bit video
Positive Response Latency Mean: 1048.65, Standard Deviation: 6.74

XP SP2 P4 2.4 GHz, USB mouse, no rate modifications (not much difference 
with qPIO12 removed) 8 bit video
Positive Response Latency Mean: 1048.65, Standard Deviation: 6.40

XP SP2 P4 2.4 GHz, USB mouse, 1000Hz rate modifications 8 bit video
Positive Response Latency Mean: 1048.70, Standard Deviation: 5.65

XP SP2 P4 2.4 GHz, USB mouse, 1000Hz rate modifications 16 bit video
Positive Response Latency Mean: 1048.64, Standard Deviation: 5.72

     Fairly lackluster results had me suspecting that the 8 bit video mode 
was the cause of the high variability but it would appear not to be the 
case given the last 16 bit test.  The likely explanation is that there is a 
large amount of software between DMDX and the actual mouse (for instance 
all mice are aggregated as a single mouse) so I located a  Microsoft 
SideWinder Plug & Play Game Pad and gave it a run through:

XP SP2 P4 2.4 GHz, USB sidewinder gamepad, no rate modifications 16 bit video
Positive Response Latency Mean: 1048.69, Standard Deviation: 2.61

XP SP2 P4 2.4 GHz, USB sidewinder gamepad, 1000Hz rate modifications 16 bit 
video
Positive Response Latency Mean: 1048.67, Standard Deviation: 1.33

     Here we can see some significant improvement percentage wise but the 
raw device was already performing rather well to begin with.


                                                /"\\
  -jonathan (j.c.f.)                            \\ /
                                                 X
     ASCII RIBBON CAMPAIGN - AGAINST HTML MAIL  / \\

The first riddle I ever heard, one familiar to almost every Jewish
child, was propounded to me by my father:
	"What is it that hangs on the wall, is green, wet -- and
whistles?"
	I knit my brow and thought and thought, and in final perplexity
gave up.
	"A herring," said my father.
	"A herring," I echoed.  "A herring doesn't hang on the wall!"
	"So hang it there."
	"But a herring isn't green!"  I protested.
	"Paint it."
	"But a herring isn't wet."
	"If its just painted its still wet."
	"But -- " I sputtered, summoning all my outrage, "-- a herring
doesn't whistle!!"
	"Right, " smiled my father.  "I just put that in to make it
hard."

                             -  Leo Rosten, "The Joys of Yiddish"



