This call is issued by the Session Manager when the operator presses PrtSc.
VioPrtSc
VioHandle (HVIO) - input
VioPrtSc supports text modes 0 through 3, and 7. An Alternate Video Subsystem may want to register a replacement for VioPrtSc. An advanced video subsystem could set a graphics mode while the mode known to the base video subsystem PrtSc routine is text. Then, if the operator presses PrtSc, the printer output is unpredictable. VioPrtSc is reserved for use by the session manager. Application programs may not issue VioPrtSc.
Three beeps are generated if a hard error is detected while writing to the printer.