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XVME-956 Manual
August 1994
Reading Control Register 2 is the same. Control Register 2 is located at 674h or 675h, but its output is
controlled by the board number select logic. To read Control Register 2 of Board Number 1 at address
674h, write to register 1, at 274h, specifying Board Number 1. This will enable the output of
only
Register
2 of that module to be read (at address 674h). To check the status of the backup batteries on that module,
read bits 6 and 7. The following example is a simple assembly language routine that accesses these bits:
Table 5-21. Assembly Language Routine Example
MOV A L , 4 0 h
B
o
a
r
d
Number 1
MOV D X , 2 7 4 h
P
o
r
t
Address 274h
OUT D X , A L O u t p u t s Board Number to Control Port Address
MOV D X , 6 7 4 h S e l e c t s Control Register 2 as source of data
IN A L , D X
I
n
p
u
t
s
data from Control register 2
AND
A
L
, 1l000000b M a s k s all but Battery Monitor bits
Return will not be Zero if a battery is low
RET
R
e
t
u
r
n
5-23
