INT 2F - ASPIHOOK.SYS - INSTALLATION CHECK
        AX = C000h
Return: AL = FFh if multiplex number in use
            ES:DI -> ASCIZ signature "ASPIHOOK" if ASPIHOOK.SYS installed
Program: ASPIHOOK is a device driver for monitoring SCSI activity through an
          ASPI host manager; it is part of the Personal Measure system
          activity monitor from Spirit of Performance, Inc.
Note:   AH=C0h is the default; ASPIHOOK searches for a free multiplex number
          between C0h and FFh on which to install itself
SeeAlso: AX=C000h"PMEASURE"

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