Function 04h Auxiliary OutputWrite character to STDAUX device\driver\AUX-
entry AH 04h
DL char to send to AUX
return none
note 1) This function call does not return status or error codes. For greater
control it is recommended that you use ROM BIOS routine Int\14 or
write to device\driver\AUX- and use device\IOCTLs.
2) If Ctrl-C is has been entered from STDIN, Int\23 is executed.
3) Default is device\driver\COM1- unless redirected by DOS.
4) If the device is busy, this function will wait until it is ready.