HP Vectra Technical Reference Manual page 110

Latest change in x position for devices which return coordinates relative
to the previous position (relative devices).
Latest change in y position for devices which return coordinates relative
to the previous position.
4.3.2.2 Physical ISR Event Records
A Physical ISR Event Record is not a data structure in the truest sense, but is a set of register
definitions for inter-driver communication of input events. Tables 4.10 and 4.11 define the
Physical ISR Event Records.
Table 4.10
GID Button ISR Event Record
AH F_ISR (OOH)
DL Physical device driver's vector address / 6
BX Button information.
Bit
OFH-08H
07H
06H-OOH
Value Definition
Reserved
1 Button up
o
Button down
Button number (0-7)
DH
=
Data Type
ES:O
=
Pointer to physical device driver header and Physical Describe Record.
Input System and HP-HIL 101