Data type


Default value



0x64 ( 100 )


Specifies the number of keyboard events that the keyboard driver buffers. This entry is also used in calculating the size of the keyboard driver's internal buffer in nonpaged memory pool. To determine the number of bytes to allocate for the buffer, the system multiplies the size of the KEYBOARD_INPUT_DATA structure (defined in NTDDKBD.H) by the value of KeyboardDataQueueSize.

You might consider increasing this value if the driver does not initialize or operate correctly and the System Log in Event Viewer contains the following message from the source, i8042prt :

The ring buffer that stores incoming keyboard data has overflowed (buffer size is configurable via the registry).

Note Image Note

This entry is used only when a device is installed. When the system recognizes a new device, it copies this entry to a device-specific subkey in the Enum subkey. Thereafter, it uses only the entries in Enum.