INT 7F - G8BPQ v4.00+ - HOST MODE - PORT CONTROL/INFORMATION
        AH = 08h
        AL = stream number (01h-40h)
Return: ES:DI -> 10-byte buffer containing blank-padded callsign
        ---v4.05+ ---
        AL = radio port to which channel is connected (level 2)
        AH = session type (see below)
        BX = L2 paclen for session
        CX = maximum frame size
        DX = L4 window size or 0000h if not L4 circuit
Program: the G8BPQ AX25 Networking Package is amateur packet radio software by
          John Wiseman which allows a PC to act as a node in an AX.25 network
SeeAlso: AH=01h"G8BPQ",AH=02h"G8BPQ",AH=03h"G8BPQ",AH=0Ah"G8BPQ"

Bitfields for session type:
 bit 0  L2LINK
 bit 1  SESSION
 bit 2  UPLINK
 bit 3  DOWNLIND
 bit 5  BPQHOST

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