Computer Hardware User Manual

2–30
Parallel port register bit definitions (Table 2– 23):
Table 2– 23. Standard and PS/2 Mode Register Bit Definitions
Signal
Name Full Name Description
TMOUT Time-out Valid only in EPP mode , this signal goes true
after a 10 µS time-out has occurred on the
EPP bus. This bit is cleared by reset.
ERR* Error Reflects the status of the -ERROR input. 0
means an error has occurred.
SLCT Printer selected
status
Reflects the status of the SLCT input. 1 means
a printer is on-line.
PE Paper end Reflects the status of the PE input. 1 indicates
paper end.
ACK* Acknowledge Reflects the status of the ACK input. 0
indicates a printer received a character..
BUSY* Busy Reflects the complement of the BUSY input. 0
indicates a printer is busy.
STB* Strobe This bit is inverted and output to the -STROBE
pin.
AUTOFD Auto feed This bit is inverted and output to the -AUTOFD
pin.
INIT* Initiate output This bit is output to the -INIT pin.
SELIN* Printer select
input
This bit is inverted and output to the pin. It
selects a printer.
IRQE Interrupt request
enable
When set to 1, interrupts are enabled. An
interrupt is generated by the positive-going -
ACK input.
PCD Parallel control
direction
When set to 1, port is in input mode. In printer
mode, the printer is always in output mode
regardless of the state of this bit.
PD0-PD7 Parallel Data Bits