INT 2F - AVATAR(Advanced Video Attribute Terminal Assembler and Recreator) A set of control codes which may be used to affect the output of characters to the screen on systems equipped with an appropriate driver.	 Similar in intent to ANSI sequences, AVATAR has shorter command sequences and provides additional PC-specific functionality. AVATAR is primarily used by the Opus and Maximus bulletin board systems (it was designed by one of the developers of the Opus system). Serial Dispatcher - INSTALL IRQ3 HANDLER
	AX = 1A42h
	BX = 4156h ('AV')
	ES:DI -> FAR handler for serial port using IRQ3
	DS = data segment needed by handler
Return: AX = status/return value
	    0000h if no more room
	    1A42h if ASD not installed
	    else handle to use when uninstalling
Notes:	the handler need not save/restore registers or signal EOI(End of Interrupt) A particular command sent to the interrupt controller to indicate that the interrupt has been handled by software and that new interrupts of the same or lower priority may now be signalled by the interrupt controller. to the
	  interrupt controller
	the handler should return AX=0000h if the interrupt was meant for it,
	  and either leave AX unchanged or return a non-zero value otherwise
	the most recently installed handler will be called first, continuing
	  to earlier handlers until one returns AX=0000h
SeeAlso: AX=1A43h,AX=1A62h