Technical information

Serial Solutions NewBIOS Reference
Service AEH, Get Number Ports._____________________________
Compatibility._____________
NewBIOS service only, ignored by PC ROM BIOS.
Parameters.___________
AH = AEH Denotes service AEH
Return Values._____________
AX = Number ports set up.
Meaning._________
Service AEH returns the number of ports that have been
set up. It reads through the list of addresses and counts those
that are set (that is are non-zero).
Other Points.____________
If the ports are allocated sequentially (ie for ’n’ ports set
COM1 to COMn are set and COMn+1 onwards are unset), the
number returned by this service can be used to filter references
to unset ports- these are ports beyond COMn.
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