IBM Personal System/2 CL57 SX - Optional Communication Adapter Slot

1.2.8 Optional Communication Adapter Slot
This option slot can accept either a secondary serial adapter or an
internal data/fax modem. The serial adapter complies with EIA-232D
standard and provides alternative input/output capabilities that have the
same function as the primary serial connector on the rear of the system.
The internal data/fax modem is a dual-function modem that can operate as a
G3 facsimile as well as a data modem.
IBM PS/2 Model CL57 SX HMR
Optional Communication Adapter Slot
_ Copyright IBM Corp. 1991
1.2.8 - 1