INT 69 - 10NET v5.0 - SYSSVC.COM - ???
        AX = 4001h
Return: CF clear
        AX = 0000h
        ES:SI -> ???
Note:   INT 69 is the default, and may be set to any interrupt from 60h-7Fh;
          the signature "SYSV" immediately before the interrupt handler serves
          as the installation check
SeeAlso: AX=4002h
Index:  installation check;10NET SYSSVC

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