Int 2F Fn 8001  - Cs_tsr Specification - Get Handle (tsr-specific Install  [t]

   AX = 8001h
   DS:SI -> ASCIZ signature string for desired TSR (see below)

Return: BX = process handle or 0000h if specified TSR not installed
   ES:DI -> process block for TSR (see AX=8000h"CS_TSR") if BX<>0000h

Note:  A widely-available copy of ASCII billing itself as "ASCII 2.OO by
     Nick Zaikin Jr." is in fact a hacked copy of the Compact Soft
     ASCII v4.23 which is identical except for the changed attribution
     and version (in fact, some instances of "4.23" were missed); the
     hacked copy requires the signature string
     "ASCII 2.OO by Nick Zaikin Jr." instead of the unhacked version's
     simple signature "ASCII"

See Also: AX=8000h"CS_TSR",AX=8002h"CS_TSR"

Values for signature strings:
 "ASCII"   ASCII, a popup ASCII table with character input
 "Halculator"  HALC, a 32-bit RPN WYSIWIH calculator with undo and ptr support
 "AntiTurbo"   AT!, an intelligent system slow-down utility