INT 2F - CS_TSR specification - TSR INSTALLATION CHECK
        AX = 8000h
        DS:SI -> 4-byte CS_TSR signature (11h 43h 53h 10h)
Return: AL = status
            00h no CS_TSR-compliant TSRs installed
            01h installed, but signature did not match
            FFh installed, signature matches
                ES:DI -> resident process block (see below) of last installed
                          TSR (if DS:SI pointed at signature on entry)
Program: the CS_TSR specification is a standardized TSR interface by Compact
          Soft group in Kiev, Ukraine
Desc:   determine whether any CS_TSR-compliant TSRs are installed on the
          selected multiplex number
Note:   AH=80h is the default, but any multiplex number from 80h to FFh may be
          used
SeeAlso: AX=8001h"CS_TSR",AX=8002h"CS_TSR",AX=8003h"CS_TSR"

Format of process block:
Offset  Size    Description
 00h  4 BYTEs   CS_TSR signature 11h 43h 53h 10h
 04h    BYTE    INT 2F multiplex number
 05h    WORD    virtual process handle (unique among loaded TSRs)
 07h  2 BYTEs   version (binary minor version, then major version)
 09h    WORD    PSP segment of TSR
 0Bh    DWORD   pointer to ASCIZ program name
 0Fh  3 BYTEs   program creation date (day, month, year)
 12h  3 BYTEs   process start time (seconds, minutes, hours)
 15h  3 BYTEs   process start date (day, month, year)

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