XVME-682 Manual
October, 1989
6.2.5 VMEbus Short I/O Address Space
Any 80286 references to bytes in address space FD0000-FDFFFF will reference the VMEbus
short I/O address space. The lower 16 bits of the 80286's address bus will be used to select a
byte in the 64K short I/O space. Note that the 80286 must be in protected mode to access the
short I/O in this fashion.
6.3 XVME-682 I/O PORT ADDRESSES
The XVME-682 I/O map contains all the I/O ports of the
IBM
AT architecture and some
additions. Six extra I/O ports are defined at
I/O
address space 30-35H. These 8-bit I/O ports
are mapped as follows:
I/O PORT ADDRESS
I/O PORT NAME ACCESS
30H C O N R E G I N \ O U T
31H
A
U
X
INT
I
N
ONLY
32H S T A T U S 1
I
N
ONLY
33H S T A T U S 2
I
N
ONLY
34H
V
M
E
Hi— ADD O U T ONLY
35H T R I G WUT I N \ O U T
The
following sections discuss these six
I/O
ports.
6.3.1 CONREG
This input\output port is the control register used to control many module functions. All bits
of this port are set to zero when the module is reset. Its bits are defined as follows:
DO = 0 The watchdog timer is disabled.
DO = 1 The watchdog timer is enabled.
D1 = 0 The FAIL LED is on and the 682 is asserting SYSFAIL.
D1 = 1 The FAIL LED is off and the 682 is not asserting SYSFAIL.
D2 = 0 The PASS LED is off.
D2 = 1 The PASS LED is on.
D3 = 0 The VMEbus requester is to release the VMEbus.
D3 = 1 The VMEbus requester is to acquire the VMEbus.
D4 = 0 Auxiliary NMI sources are disabled.
D4 = 1 Auxiliary NMI sources are enabled.
6-5
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