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If DELINH jumper E13 to E14 is connected, then selecting the printer
will also cause a prime condition.
If jumper E14 to E15 is used, select
will not cause a prime condition.
4.4 DATA INPUT
Inputs to the printer consist of seven standard parallel data lines
(DATAl-DATA7), an optional DATA8 line, an active low DATA STROBE input, and
an active low INPUT PRIME line. The first seven data lines represent the
7 bit USASCII code shown in Series 300 Operators Manual. The optional
eighth bit is used as a control bit either for specifying an elongated
character or for selecting an additional character set. The data strobe
is used to synchronize the input data with the printer electronics. The
prime line is used to prime (initialize) the printer electronics.
The eight data inputs have a unity loading factor and are termi-
nated by a lK pull-up resistor to +5 volts. The data strobe and prime
inputs are terminated by a 470 ohm resistor to +5 volts.
Note that with
no input on DATA8 line, terminating resistor R15 holds the input at +5V,
making bit 8 appear as a ONE on the logic card.
In response to received data, the printer generates an Acknowledge
pulse to acknowledge reception of a character.
If the received character
caused the printer to perform some function such as paper movement,
character printing, etc., the printer responds with a Busy signal.
4.4.1
DATA INPUT TIMING
In general, the data transfer sequence consists of the input
device placing the appropriate code on the data lines to the printer and
then generating a data strobe pulse. The printer, after a slight delay,
responds with an acknowledge pulse. Or if the received data caused a
busy condition, the printer
firs~
activates the busy line for the duration
of the busy condition and then responds with an acknowledge pulse.
Rev. E
4-6
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