AT&T PC 6300 - Page 444

MAINTENANCE
Faulty RAM chips are determined by comparing the binary data
written to the binary data read. By knowing which data bit is
faulty, you can locate the faulty RAM chip as shown below:
Example:
Data Written in HEX - AAAA
Data Read in HEX - ABAA
Bit Position 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
00 00 000100000000
5-66
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0
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Binary Data Written 10 10 101010101010
Binary Data Read -10 10 10 1110 10 10 10 f ^
n
In the above example, the faulty data bit is bit 8. Therefore, the
bad chip is the eighth chip in the bank. Figures 5-16 and 5-17 m
show the RAM chip locations in each bank. \
n
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h
I f
0
0
fi
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