Parallel interface signals, Signal Meaning

Parallel interface signals

The following table provides details for the signals used on the printer’s parallel interface. Note descriptions in [ ] are for high-speed mode of the parallel interface.

Signal	Meaning

Strobe* [nStrobe] (Pin 1)	A negative-going Strobe* pulse causes the printer to read and latch
	the data on the Data 0 [1] to Data 7 [8] signal lines.

Data 0 [1] to Data 7 [8]	These eight signals form the data byte sent from the host computer to
(Pins 2 to 9)	the printer. Data 7 [8] is the most significant bit and Data 0 [1] is the
	least significant bit.

Acknowledge* [nAck]	This signal is returned to the host computer. This negative-going pulse
(Pin 10)	acknowledges the previous character received by the printer.
	Acknowledge* pulses are sent only when Busy is low.

Busy [Busy] (Pin 11)	This signal is returned to the host computer. This signal is high when
	the printer is busy and low when it is able to accept more data. Every
	high-to-low transition is followed by an Acknowledge* pulse.

Paper Empty [PError]	This signal is returned to the host computer. This signal goes high
(Pin 12)	when the printer runs out of paper.

On-Line [Select] (Pin 13)	This signal is returned to the host computer. This signal is high when
	the printer is on-line and low when the printer is off-line. It goes low
	when the upper unit is raised, or when the Go key is pressed to set the
	printer off-line.
	Note: The Paper Empty and On-Line signals are not used unless
	enabled by the FRPO command (O2 parameter).

Auto-Feed [nAutoFd]	This signal is used in the Epson version of the Centronics interface to
(Pin 14)	receive a carriage return. In high-speed mode, it is used as an interrupt.

+5 V DC (pin 18)	This line is connected to the printer’s +5 V DC line (+5 V ±0.5 V, 400
	mA maximum, fused).

Prime [nInit] (Pin 31)	This signal is used in the standard Centronics interface to enable the
	computer to reset the printer. It is ignored by the printer.

Error* [nFault] (Pin 32)	When the high-speed parallel line control is on (FRPO O2 = 2), this

	line returns error status to the host computer.

Auxiliary output 1 (Pin 33)	This signal line is not used.

Power Ready (Pin 35)	This signal is high when the printer’s power is on.
Select In [NSelectIn]	This signal is used in some versions of the Centronics interface to
	enable the computer to force the printer on-line. In high-speed mode,
	it is used as an interrupt.


	FS-1010

C-5