)
Values for Digiboard CCB command number:
 40h	Set Receive Mid Water Mark
 41h	Set Receive High Water Mark
 42h	Flush Receive Buffer
 43h	Flush Transmit Buffer
 44h	Transmit Pause
 45h	Transmit Resume
 46h	Set Interrupt to Host Mask
 47h	Set Baud, Data, Stop and Parity
 48h	Send Break
 49h	Set Modem Lines
 4Ah	Set Break Count
 4Bh	Set Handshake
 4Ch	Set Xon/Xoff Characters
 4Dh	Set Transmit Mid Water Mark
 4Eh	IRQ Polling Timer to Host
 4Fh	Buffer Set All
 50h	Port On
 51h	Port Off
 52h	Receive Pause
 53h	Special Character Interrupt
 54h	RS-422 Enable