PsychtoolboxKernelDriver

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PsychtoolboxKernelDriver - A low level support driver for Apple OS-X

The PsychtoolboxKernelDriver (PKD) is a MacOS-X kernel extension (a
kext). It currently should work with AMD/ATI Radeon graphics cards of the
X1000, HD2000, HD3000 and HD4000 series. It doesn't work with graphics chips from
other manufacturers and probably doesn't work with older ATI chips. It
works to some degree with the most recent HD-5000 series chips and later.

The driver needs to be manually loaded by a user with administrator
privileges and provides a few special services to PTB-3, ie., PTB's
functionality is extended/enhanced if it detects such a driver at startup
time:

* Beamposition queries (See help BeampositionQueries) allow for
especially robust and accurate stimulus onset timestamping. They are
supported by OS-X on all PowerPC systems and on Intel based systems with
NVidia graphics cards, but not on Intel systems with ATI graphics. The
driver restores this functionality on single display and dual display
setups.

* Multihead display sync: The driver allows to synchronize the display
refresh cycles of the displays connected to a multihead graphics card
to allow for high quality tear-free binocular and stereo stimulation of
subjects.

* Use of 10 bit per color component framebuffers: The driver enables two
extra bits of color output precision per color channel on your card,
allowing for 1 billion shades of different colors instead of the 16.8
million colors available without the driver.

* The driver implements workarounds to fix some problems caused by
graphics driver and operating system bugs when the graphics card is used
with high color/luminance precision display devices like the CRS Bits+ or
Bits# boxes, or the VPixx Inc. DataPixx and ViewPixx devices, and similar
equipment.


The driver only works if a *single* graphics card (single-head or
dual/multi-head) is installed in your machine. It won't work reliably if
more than one card is installed.

As this driver accesses the hardware at a very low level, bypassing the
whole operating system, its graphics subsystem and the drivers from ATI,
there is some potential for things to go wrong. Although our testing so
far didn't show any such problems, it may happen on your system. That is
why this driver is an *experimental* feature and why you need to have
administrator privileges to enable/load the driver.

How to install (one time setup):

Unzip the file Psychtoolbox/PsychAlpha/PsychtoolboxKernelDriver.zip, then
copy the driver PsychtoolboxKernelDriver.kext into a system folder, e.g.,
/System/Libary/Extensions/
The location doesn't really matter, but that is the common place for such
.kexts. You must do this from the terminal via:

sudo cp -R PsychtoolboxKernelDriver.kext /System/Library/Extensions/

assuming the unzipped driver is in your current working directory.

How to enable (each time after restarting your system):

In a terminal type:
sudo kextload /System/Library/Extensions/PsychtoolboxKernelDriver.kext

Both sudo commands will ask you for your password.

USE THIS DRIVER AT YOUR OWN RISK - BUGS OR MALFUNCTIONS MAY CRASH YOUR

MACHINE AND CAUSE DATA LOSS!