IBM PS/2 35 SX Hardware Maintenance Reference page 16

IBM PS/2 Model 35 SX, 35 LS, 35 SLC HMR
Parallel Port
1.2.6 Parallel Port
The parallel port allows the attachment of devices that accept eight bits
of parallel data at standard transistor-transistor-logic (TTL) levels.
The port has a 25-pin, D-shell connector and is designed primarily for
printers. However, the port can be used as a general input/output port
for any device or application that matches its input/output capabilities.
The connected device is identified (addressed) by system configuration as
Parallel 1, Parallel 2, or Parallel 3.
¦ Copyright IBM Corp. 1991, 1992
1.2.6 - 1