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C •
6 BACK-UP PORT
Although this system contains the resume function, 82CS9
(PIC) and 82CS3 (timer) have registers which can not be
read, and consequently they can not be backed up for
resuming the system.
For this reason, when writing the data, the content of these
registers must be copied into another readable register.
Reading this register can be executed by setting the Index
address to the Index register in order to read the data
register.
The following table shows the Index address and the contents
to be read out.
TABLE C-2
Index Address and Contents
Index Register
Contents to be read in the Port-OFH
50
82C53 Control Word Register, #0
51
n
#2
52
82C59 Initialize Command Word 1
53
n
2
54
n
4
I/O Back-up Index Register
I/O Back-up Data Register
OFOH
OFlH
Both Index register and Data Register are in the "clearn
status when power is on.
On writing data, the address of the above S registers are as
follows:
CWR#O (82CS3)
CWR#2 (82CS3)
ICWI
( 82CS9 )
ICW2
(82CS9)
ICW4
(82CS9 )
043H and moreover, bit 6 and 7 of the
write data are "0".
043H and moreover, bit 6 of the write
data is "0", and
7
nl".
020H and moreover, bit 4 of the write
data is nl".
02lH
02lH (data is written after the address
ICW2).
C - 9
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