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Chapter 6. Service Request Function
6.7 SVC_REQ 6: Change/Read Number of Words to Checksum
Use SVC_REQ 6 to read the current word count in the program to be check-summed or set a new
word count. By default, 16 words are checked. The function is successful unless some number other
than 0 or 1 is entered as the requested operation.
The parameter block has a length of 2 words.
6.7.1
To read the word count:
Enter a zero in the first word of the parameter block.
Address
0
Address +
Ignored
1
The function returns the current checksum (word count) in the second word of the parameter block.
No range is specified for the read function; the value returned is the number of words currently being
check-summed.
Address
0
Address +
Current word count
1
6.7.2
To set a new word count:
Enter a one in the first word of the parameter block and the new word count in the second word.
Address
1
Address +
New word count
1
The CPU changes the number of words to be check-summed to the value given in the second word of
the parameter block, rounded up to the next multiple of 8. To disable check-summing, set the new
word count to 0.
284
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
GFK-2950C
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