Exception Table Entry Format - NCR 7158 Owner's Manual

7-144 Chapter 7: Programming Guide

Exception Table Entry Format

Each exception table entry consists of five words. The first two words
contain the first eight characters of the transit number by packing the
low order nibble of the numeric transit number characters. For
Canadian checks, eliminate the dash and store the eight numerics.
The next three words are used as six individual bytes to tell the
firmware how to interpret the MICR characters that fall to the right of
the rightmost transit symbol. Each of the six bytes is positional and
consists of two parts: character type and number.
The three high order bits of each byte mark the character type. The
characters can be marked in three ways: check serial # character,
account # character, or "skip this character or symbol."
The five low order bits of each byte contain the number of characters of
that type to extract. Most exceptions will not need to use all six bytes;
in that case clear the unused bytes to zero.
Bits within Byte
check serial # character string
account # character string
character string to ignore
Example 1
t123456780t12349876543210o 1234 is the check serial #
9876543210 is the account #
To load the second table entry, which starts at word 25, the transit
number 123456780 would be stored in the first two words of its table
entry using this string of commands:
0x1B 0x73 0x12 0x34 25
0x1B 0x73 0x56 0x78 26
After the right transit symbol are immediately the four characters of
the check serial #, followed immediately by the ten characters of the
account number. These would be bitwise encoded as:
7 6 5 4 3
0 0 1 n n
0 1 0 n n
1 0 0 n n
2 1 0
n n n
n n n
n n n