INT 61 - Banyan VINES - GET USER NAME
        AX = 0007h
        BX = 0005h
        DS:DX -> 64-byte buffer for user's StreetTalk name
Return: AX = status
            0000h successful
            0001h network software not installed or incompatible
Note:   if no user logged in, first byte of returned name will be 00h