Radio Shack TRS-80 CR-510, Руководство по эксплуатации

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Under this format, the Card Reader expects one marking per field. Byte 1 consists of the ASCII code
of the character represented by the marked row of Field One. Byte 2 consists of the ASCII code of
the character represented by the marked row of Field Two. For example if Row 0 is marked, then
Byte 1 is equal to 66 (the ASCII code for "B").
If there are no row markings in a field, then the corresponding byte equals 63 (the ASCII code
for "?'). If there is more than one row marking in a field, the Card Reader looks for the most
dominant marking. If it cannot determine which is dominant, then the corresponding byte is returned
as 62 (the ASCII code for ">").
Note: GR1 and GR2 are recommended for multiple-choice test scoring program development.
GR2
GRader 2
Converts the data into two 6-bit fields, reading from right to left, as follows:
(•means the row is marked.) Marking more than one 0-9 row in a given column will result in a
reverse slash.
GR1
GRader 1
Converts the data into two 6-bit fields, reading from right to left, as follows: