HP (Hewlett-Packard) E1432A Graphics Tablet User Manual


 
q Control Register: A write to this register causes specific actions to be executed
by the device. The actions are described in the following table.
Bit 15 14-2 1 0
Contents
A24/A32
Enable
Unused Sysfail Inhibit Reset
A24/A32 Enable: A one (1) in this field enables access to the devices A24
VME Bus registers. A zero (0) disables such access.
Sysfail Inhibit: A one (1) disables the device from driving the SYSFAIL*
line.
Reset: A one (1) forces the device into a reset state.
q Offset Register: This read/write register defines the base address of the devices
A24 registers. The four most significant bits of the Offset register are the values
of the four most significant bits of the devices A24 register addresses. The 12
least significant bits of the Offset register are always zero (0). Thus, the Offset
register bits 15-12 map the VME Bus address lines A23-A20 for A24 register
accesses. A read of the Offset register always returns the address offset most
recently written to the Offset register.
q Port Control Register: This register is used to override the Local Bus control of
the device. (This applies to HP E1432A modules that are equipped to use Local
Bus). It has the following format:
Bit 15-2 1 0
Contents Unused
LBus
Pipe
LBus
Enable
LBus Pipe: Writing a one (1) puts the Local Bus into pipeline mode, if the
LBus Enable bit is also set. Writing a zero (0) allows the Local Bus to
operate in some other mode.
LBus Enable: Writing a one (1) enables the Local Bus interface. Writing a
zero (0) disables the local bus interface. RESET VALUE: 0
HP E1432A User's Guide
Register Definitions
A-7