// TSR_3 Example //Scout

equals  _KeyboardFlags  = 0417h

(expr	Terminate (?)
	ax=4C^1; 21h=.int
expr)

(expr	JumpFAR ?) -> bytes   =0EAh, ^1(4)

(expr	FreeEnvironment
	es=WORD PTR ds:[2Ch]
	ah=49h; 21h=.int
expr)

(expr	TSR (?)
	dx=OFFSET ^1; 27h=.int
expr)

(expr	FreeMemory
	ah=49h; 21h=.int
expr)

equals  Request         =       0ABBAh,
        Reply           =       0BABAh,
        HotKey          =       1C0Dh,
        ShiftStatus     =       00000001b

equals  BufferSize      =       0

        MODEL   Tiny, Pascal
        .ORG    100h
        PROGRAM TSR_3
        .LOCALS _@

	goto	Initialize

bytes   Flags           =       00000000b,
        SaveAH

(proc	FAR	Int_16h()[]
        (if cs:Flags.test.00000001b=
          (if ah.test.11101110b<>
	    if ax<>Request goto Pass_16h
	    ax=Reply; push cs; pop es; .iret
	  if)
          (if ah.test.00000001b=
	    (while
	      cs:SaveAH=ah
	      .sti; .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
              if ax<>HotKey then .iret
              call ChkShiftStatus()
              if <> then .iret
              call Main()
	      ah=cs:SaveAH
	    while)
	  if)

	  cs:SaveAH=ah; cs:SaveAH=-1
	  .sti; .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
          (if <> and ax=HotKey
            call ChkShiftStatus()
            if <> then 2=.retf
	    ah=cs:SaveAH
	    .pushf; .cli; call DWORD PTR cs:Old_Int_16h()
            call Main()
	  if)

	  2=.retf

	if)

Pass_16h:
	JumpFAR Old_Int_16h
proc)

(proc   ChkShiftStatus()[ax,es]
        es=ax=0
        al=BYTE PTR es:[_KeyboardFlags]; al=.and.00001111b
        al=.cmp.ShiftStatus
        return
proc)

(proc   Main()[ax]
        cs:Flags=.or.00000001b

//      [ Куча всего ]
//      Например:

        ax=0E07h; 10h=.int
//

        cs:Flags=.and.11111110b
        return
proc)

Initialize:
// Проверить наличие себя в памяти
	ax=Request; 16h=.int
	(if ax<>Reply
          ax=3516h; 21h=.int
          WORD PTR [Old_Int_16h]=bx
          WORD PTR [Old_Int_16h+2]=es
          dx=OFFSET Int_16h
          ah=25h; 21h=.int

          FreeEnvironment

          TSR (Initialize+BufferSize)
	if)
// UnInstall
        dx=es
        ax=3516h; 21h=.int
        bx=-OFFSET Int_16h
        ax=es-dx.or.bx
        if <> goto Finish

        dx=.lds.DWORD PTR es:Old_Int_16h
        ax=2516h; 21h=.int

	FreeMemory
Finish:
	Terminate (00h)