HP Vectra Technical Reference Manual page 107

An example of device mapping and emulation occurring in the system is the translation of mouse
input to Cursor Control Pad (CCP) input. Since standard DOS processes keyboard input only, (not
mouse input), the physical GID driver which processes mouse input is mapped, in its default
state, to a driver called V_PGID_CCP. This driver causes mouse input to emulate input from the
CCP. For an application which processes industry standard mouse input (INT 33H) to use the HP
Mouse, the mouse physical GID driver should be mapped to the V_LHPMOUSE driver using the
F33_INSTALL function (see Section 6 for more details).
4.3.2 Data Structures
The hardware interface level uses two major data structures: the Physical Describe Record and
the Physical ISR Event Record(s). These data structures help keep track of the numerous events
occurring in the Input System.
4.3.2.1 Physical Describe Record
The Physical Describe Record is used by the physical GID drivers to keep track of the current state
of their respective devices. Each of the physical GID drivers has a Physical Describe Record
associated with it, which is located directly after the driver header starting with memory address
DS:001 OH. An explanation of the Physical Describe Record fields follows, table 4.9 contains the
field types and offsets.
98 Input System and HP-HIL