INT 2F - HyperWare programs - INSTALLATION CHECK
        AX = DF00h
        BX = product code
            4248h ('BH') HyperStb
            4448h ('DH') HyperDisk v4.20+
            4B48h ('KH') HyperKey
            5348h ('SH') HyperScreen
        CX = 0000h
        DX = 0000h
Return: AL = status
            00h not installed
            FFh multiplex number in use
                CX = 5948h ('YH') if selected product installed
                ---HyperDisk---
                BX = code segment of resident portion
                DX = HyperDisk local data version
Program: HyperDisk is a shareware disk cache by HyperWare (Roger Cross)
Note:   AH=DFh is the default; if it is already in use by some other program,
          HyperWare programs then scan multiplex numbers from C0h through FFh
SeeAlso: INT 13/AX=8EEDh
Index:  installation check;HyperDisk|installation check;HyperStb
Index:  installation check;HyperKey|installation check;HyperScreen
Index:  HyperDisk;installation check|HyperStb;installation check
Index:  HyperKey;installation check|HyperScreen;installation check

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