IBM 1220 User Reference page 180

PS SmartSwitch
Purpose:
To configure the printer so it automatically switches to PostScript emulation when a print job received
through the parallel port requires it, regardless of the default printer language.
Values:
On* Printer examines data on the parallel interface and selects PostScript emulation if the data
indicates that is the required printer language.
Off Printer does not examine the incoming data. The printer uses PCL emulation to process the
job if PCL SmartSwitch is On, or uses the default printer language specified in the Setup
Menu if PCL SmartSwitch is Off.
See also:
PCL SmartSwitch;
Protocol
Purpose:
To specify the parallel interface protocol.
Values:
Standard
Fastbytes*
Printer Language
May resolve some parallel interface problems.
Provides compatibility with most existing parallel interface implementations
(recommended setting).
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