Honeywell 400 Series Hardware Manual page 14

READERS
The reading of each card is initiated by a specific sequence of instruction signals received
by the card reader. If no Attention conditions exist, the card reader goes into a busy
state, decodes the instruction,.checks its validity, and initiates the prOper. control functions.
The first card is released from the input hopper. The card track moves the Card to the
reading station. There, the photocells read the card, one column at a time. The photocells
detect light from the light source passing through the punched holes in the columns and
send an electronic signal to the control electronics. In each card cycle, the Operation of
the photocells in the read station is checked to determine that there is no malfunction
and that the card has not been unstable in its passage through the read area.
PUNCHES
Before punching can begin, the card punch must be properly loaded and free of any Attention
conditions. The subsystem becomes busy and card punching begins when a punch instruction
is received and accepted.
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