INT 61 u - PC/TCP kernel v2.05 - "net_write" - ???
        AH = 1Ah
        BX = connection handle???
        CX = ???
        DX = ???
        DS:SI -> ???
Return: CF clear if successful
            AX = ???
            DX = ???
        CF set on error
            AX = error code (see INT 61"PC/TCP")
Notes:  the installation check consists of testing for the signature "TCPTSR"
          three bytes beyond the start of the interrupt handler
        INT 61 is the default; PC/TCP v2.05 may be configured to use any
          interrupt from 20h through E0h
SeeAlso: INT 61/AH=00h"PC/TCP",INT 61/AH=1Bh,INT 61/AH=1Ch