mouse and keyboard buffer

[Bert Hindriks]

How can I increment the values for the mouse- and the keyboardbuffer in the
register in NT?? What is a good value (now I get a warning that the two
buffers are too small)

Replies to: be...@freemail.nl

[Jerold Schulman]

Intel 8042 Port Driver Entries
==============================

The i8042prt driver handles the keyboard and mouse port mouse (also known
as a PS/2-compatible mouse) for the Intel 8042 controller. These value
entries are found in the following subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\i8042prt\Parameters

KeyboardDataQueueSize REG_DWORD >= 0x1
Specifies the number of keyboard events to be buffered internally by the
driver, in nonpaged pool. The allocated size, in bytes, of the internal
buffer is this value times the size of the KEYBOARD_INPUT_DATA structure
(defined in NTDDKBD.H). Consider increasing the size if the System log in
Event Viewer contains the following message from the i8042prt source: "The
ring buffer that stores incoming keyboard data has overflowed (buffer size
is configurable via the Registry)."
Default: 0x64 (100)

KeyboardDeviceBaseName REG_SZ Base keyboard port device name
Specifies the base name for the keyboard device object(s) created by the
i8042prt device driver. The device driver also writes information about the
device objects into HKEY_LOCAL_MACHINE\HARDWARE\DeviceMap so that the
keyboard class driver can locate the keyboard port device objects.
Default: KeyboardPort

MouseDataQueueSize REG_DWORD >= 0x1
Specifies the number of mouse events to be buffered internally by the
driver, in nonpaged pool. Consider increasing the size if the System log in
Event Viewer contains the following message from the i8042prt source: "The
ring buffer that stores incoming mouse data has overflowed (buffer size is
configurable via the Registry)."
Default: 0x64 (100)

MouseResolution REG_DWORD Mouse resolution specifier
Used in specifying the mouse port mouse resolution, where 2 to the power of
MouseResolution specifies counts-per-millimeter.
Default: 0x3

MouseSynchIn100ns REG_DWORD Time, in 100 nanosecond units
Specifies the length of time after which the next mouse interrupt is
assumed to indicate the start of a new mouse packet (partial packets are
discarded). This allows the driver to synchronize its internal notion of
the mouse packet state with the hardware state, in the event that a mouse
interrupt has been lost. Consider modifying this value if the system
behaves as if there are random mouse events occurring (for example, button
clicks when no mouse button has been pressed).
Default: 10000000 (1 second)

NumberOfButtons REG_DWORD >= 0x1
Specifies the number of buttons on the mouse port mouse. If an incorrect
number of buttons is detected at startup time and placed in the Registry,
this value can be used to override it.
Default: 0x2

PointerDeviceBaseName REG_SZ Base mouse port device name
Specifies the base name for the pointer device object(s) created by the
mouse port mouse driver. The device driver also writes information about
the device object into HKEY_LOCAL_MACHINE\HARDWARE\DeviceMap so that the
pointer class driver can locate the pointer port device objects.
Default: PointerPort

PollStatusIterations REG_DWORD Number
Specifies the maximum number of times to check the i8042 controller status
register for interrupt verification before dismissing the interrupt as
spurious. This value can be used to work around a problem experienced on
some hardware (including the Olivetti MIPS computers) where the keyboard
interrupt is raised before the Output Buffer Full bit is set in the i8042
status register.

Increase this value if the system seems to suddenly stop taking keyboard
interrupts. This can happen if a keyboard interrupt is mistakenly dismissed
as spurious, when instead it just took too long to set Output Buffer Full
after raising the interrupt. Increasing the value of PollStatusIterations
results in a longer execution time for the Interrupt Service Routine if the
keyboard interrupt truly is spurious (there is a 1 microsecond delay
following each check for Output Buffer Full).

To determine whether the driver is taking keyboard interrupts, press the
NUMLOCK key. If the NumLock light on the keyboard turns on or off, this
indicates that the i8042prt driver handled the keyboard interrupt
correctly. Default: 1

OverrideKeyboardType REG_DWORD >= 0x0
This entry is not usually present. When present, it specifies the keyboard
type (overriding the keyboard type detected during system initialization).
Add this value entry if the detected keyboard type is incorrect in the
Registry. Type values 0x2 and 0x4 indicate an enhanced 101-key or 102-key
keyboard, or compatible; other values typically indicate an old-style AT
keyboard (83, 84, or 86 keys), or compatible.
Default: 0x4 (Enhanced 101-key or 102-key keyboard)

OverrideKeyboardSubtype REG_DWORD >= 0x0
This entry is not usually present. When present, it specifies the OEM-
dependent keyboard subtype (overriding the keyboard subtype detected during
system initialization).
Default: 0x0

PollingIterations REG_DWORD >= 0x400
Specifies the standard number of times to poll the hardware (in polling
mode) before giving up and timing out the operation. Consider increasing
this value if the driver fails to initialize or work correctly and the
System log in Event Viewer contains the following message from the i8042prt
source: "The operation on ... timed out (time out is configurable via the
Registry)."
Default: 0x400

PollingIterationsMaximum REG_DWORD >= 0x400
Specifies the maximum number of times to poll the hardware (in polling
mode) before giving up and timing out the operation. This value is used
instead of PollingIterations when an old-style AT keyboard is detected (see
OverrideKeyboardType). Consider increasing this value if the driver fails
to initialize or work correctly and the System log in Event Viewer contains
the following message from the i8042prt source: "The operation on ...
timed out (time out is configurable via the Registry)."
Default: 0x2EE0

ResendIterations REG_DWORD >= 0x1
Specifies the maximum number of times a hardware operation will be retried
before timing out. Consider increasing this value if the driver fails to
initialize or work correctly and the System log in Event Viewer contains
the following message from the i8042prt source: "Exceeded the allowable
number of retries (configurable via the Registry) on device ..."
Default: 0x3

SampleRate REG_DWORD Mouse sample rate in Hz
Specifies the sample rate for the mouse. Intended for future use. This
value might have no effect in the first release of Windows NT.
Default: 0x3C (60 Hz)

I found found that the mouse buffer needs to be increased substantially. Try
starting at 1024 instead of 100.

Jerold Schulman - Microsoft BackOffice <MVP>

JSI, Inc.
1045 Essex Court, Alpharetta, GA 30004-3811
Orders:+1-800-585-9588 Phone:+1-770-475-3820 Fax:+1-770-442-3820
Web Site: http://www.jsiinc.com Internet Mail: j...@cis.compuserve.com