Int 61 Fn 01  - Banyan Vines - Check Service                               [N]

   AH = 01h
   AL = service ID (see below)

Return: AX = status
       0000h installed
       0001h not installed
       0002h invalid ID

Values for service ID:
 01h   communications
 02h   primary 3270 emulation
 03h   async terminal emulation
 04h   file deflection
 07h   StreetTalk
 08h   environment
 0Ah   secondary 3270 emulation
 0Bh   semaphore service
 0Ch   3270 emulation active status
 0Dh   3270 keyboard interrupt simulator