Honeywell 400 Series Hardware Manual page 78

Data Formats
The CRZZOl subsystem can read data punched in either Hollerith or binary formats, or
The subsystem reads, sorts, and stacks decks of 12-row punched cards of either 80-column
or optional 51-column cards. These two types of cards cannot be intermixed. The reader
is easily converted from one type of reading to the other by the operator.
All cards must have a true leading edge between rows 0 and 1. Scored or perforated cards
require that special attention be paid to this point.
C h e c k I n g
The subsystem makes five types of checks during the card read time:
Light check--Ensures that when a card is not present, the read station transducer
register indicates a light condition.
Dark check-~Ensures that the transducer register indicates a dark condition when a
card is in the read station.
Column strobe count check--Ensures that the correct number of column strobes were
generated for a card. '
Dual read check--Ensures that data read from each column at both read stations
agrees.'
Internal parity check--Ensures that correct parity is maintained through the card
reader subsystem and is transmitted.
Operating Speeds
When the card reader is operating under correctly timed, continuous feeding conditions,
it is capable of reading cards at approximately 1200 cards per minute for 51-column cards
and 900 cards per minute for 80-column cards.
When the program calls for demand feeding, speeds vary according to the timing of the
instructions.
Timing Considerations
The program must issue a Read instruction for each card read. In order to maintain the
maximum possible feed/ read rates, the processing system must issue a new Feed or Read
instruction within 1 millisecond after receiving the preceding Terminate signal. When
instructions are delayed, the reading rate drops proportionately.
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