INT 10 - DGIS - REDIRECT CHARACTER OUTPUT
AX = 6A01h
CX = 0000h
ES:DI = address of device to send INT 10 output to
Return: CX = 0000h  output could not be redirected
else INT 10h output now routed to requested display

See also: 106A02

106A01CX0000 - DGIS - REDIRECT CHARACTER OUTPUT