Honeywell 400 Series Hardware Manual page 15

DATA MEDIA
MODES OF OPERATION'
Readers
BINARY MODE. Data punched into the top half of each column (row 12-row 3) is transmitted
as the first character, supplemented by an odd parity bit. Data read from the lower half
of the column (row 4-row 9) is transmitted as the second character.
MIXED MODE. When the card reader is operating in the mixed mode, it is reading a deck
composed of both alphanumeric and binary cards. As each card enters the reader, column
1 is examined to determine which type the card is and thus, how the data is to be handled.
If the '7' and "9" of column 1 are punched, regardless of what other punches occur in the
column, the card is read in the binary mode. If either or both of these two punches are
missing, the card is read in the alphanumeric mode. In either case, the full 80 columns of
card information are transmitted, including column 1. Since there are no alphanumeric
characters represented by both the 7 and 9 punches, either with or without other punches,
the card reader cannot accidentally misinterpret a standard Hollerith punch configuration
in column 1 for the special identifying 7 and 9 punches of a binary card.
Punches
OD Two 6-bit binary characters are punched into each card column. The
first character goes into card rows 12-3 (row 12 contains the most-significant bit). The
-3-