INT 2F U - NETWORK REDIRECTOR - PRINTER ON/OFF???
AX = 1126h
ES:DI -> SFT for file handle 4???
SS = DOS DS???
???
Return: CF set on error
Notes:  called by DOS 3.1+ kernel
called when print echoing (^P, ^PrtSc) changes state and STDPRN has
bit 11 of the device information word in the SFT set

See also: 2F1124

2F1126 - NETWORK REDIRECTOR - PRINTER ON/OFF???