Category: <b>serial I/O</b>
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<pre><b>INT 14 - Digiboard DigiCHANNEL PC/X* - GET TRANSMIT BUFFER FREE SPACE</b>

	AH = 12h
	DX = port number (00h-03h) (04h-43h for XAPCM232.SYS)
Return: AX = number of bytes free
SeeAlso: AH=0Ah"Digiboard",AH=14h"Digiboard"
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