IBM 5150 PC Technical Reference (6025005, August, 1981) (PDF)

IBM Monochrome Display &Printer Adapter
Parallel Printer Adapter
Input from address x' '3BC' Input from address 378H
This command presents the CPU with data present on the pins
associated with the out to x' '3BC'. This should nonnally reflect the
exact value that was last written to x '3BC'.1fan external device should
be driving data on these pins (in violation ofusage ground rules) at the
time of an input, this data will be 'or' ed with the latch contents.
IBM Monochrome Display & Printer Adapter
Parallel Printer Adapter
Input from address 3BDH Input from address 379H
This command presents real time status to the CPU from the pins
as follows.
Bit 1 Bit 0
IBM Monochrome Display & Printer Adapter
Parallel Printer Adapter
Input from address 3BEH Input from address 37AH
This instruction causes the data present on pins 1, 14, 16, 17 and IRQ
bit to be read by the CPU. In the absence of external drive applied to
these pins, data read by the CPU will exactly match data last written to r""'\
x' '3BE' in the same bit positions. Note that data bits 0-2 are not
included. Ifexternal drivers are dotted to these pins, that data will be
'or'ed with data applied to the pins by the x' '3BE' latch.
Bit 7 Bit 6 Bit 5 Bit4 Bit 3 Bit 2 Bit 1 Bit 0
-- --
IRQ Pin 17 Pin 16 Pin 14 Pin 1
Enable
Por={) Por=1 Por={) Por=1 Por=1
These pins assume the states shown after a reset from the CPU.
Note: For pin references see Parallel Printer Adapter Interface
Connector Specifications page 2-69.
2-68