void    NetBios(NCB *ncb_ptr)   {
        _ES    = FP_SEG( (void far *) ncb_ptr);
        _BX    = FP_OFF( (void far *) ncb_ptr);
        _AX    = 0x0100;
        geninterrupt(0x5c);   }

int     IsNetBIOS(void) {
        int_5C_vector = getvect(0x5C);
        if (int_5C_vector == NULL)
            return 0;    /* NetBIOS not loaded */

        WorkNCB.NCB_COMMAND = 0x7F;	/* 7F is an invalid command */
        NetBios(&WorkNCB);
        if (WorkNCB.NCB_RETCODE != 03)	/* 3 means invalid command */
            return 0;    /* NetBIOS not loaded */

        return 1; }   /* NetBIOS is present */