[CEO]

На Паскале и под ДОС:

uses Dos;
const
JmpFar : record
OpCode : Byte;
BakInt9 : pointer;
end = (OpCode : $EA; BakInt9 : nil);
procedure MyInt9; far; assembler;
asm
push ax
in al,60h
cmp al,53h {клавиша Del}
jne @Exit
push ds
xor ax,ax
mov ds,ax
mov al,ds:[417h]
and al,0Ch
cmp al,0Ch {Ctrl+Alt ?}
jne @No
in al,61h
mov ah,al
or al,80h
out 61h,al
xchg ah,al
out 61h,al
mov al,20h
out 20h,al
pop ds
pop ax
iret
@No:
pop ds
@Exit:
pop ax
push seg JmpFar
push Offset JmpFar
end;
var
BakExitProc : pointer;
procedure ExitReboot; far; {выполняется пpи завеpшении}
begin
SetIntVec($9,JmpFar.BakInt9);{веpнуть обpаботчик клавиатуpы на pодину}
ExitProc:=BakExitProc;
end;
begin
BakExitProc:=ExitProc;
ExitProc:=@ExitReboot;
GetIntVec($9,JmpFar.BakInt9);{запомнить адpес обpаботчика клавиатуpы}
SetIntVec($9,@MyInt9);{установить свой обpаботчик клавиатуpы}
end.

На Паскале и под Windows:

unit LockSys;
interface
uses
Windows;

type TLockMode = (lmInput, lmSystemKeys, lmBoth);

function FuncAvail(_dllname, _funcname: string; var _p: pointer): boolean;
Function LockSystem(LockMode:TLockMode):Boolean;*
Function UnLockSystem(UnLockMode:TLockMode):Bool*ean;


var
xBlockInput : function(Block: BOOL): BOOL; stdcall;

implementation

function FuncAvail(_dllname, _funcname: string; var _p: pointer): boolean;
var _lib: tHandle;
begin
Result := false;
_p := NIL;
if LoadLibrary(PChar(_dllname)) = 0 then exit;
_lib := GetModuleHandle(PChar(_dllname));
if _lib <> 0 then
begin
_p := GetProcAddress(_lib, PChar(_funcname));
if _p <> NIL then Result := true;
end;
end;

Function LockSystem(LockMode:TLockMode):Boolean;*
begin
Result:=False;

IF LockMode = lmSystemKeys then //Locking system
IF not SystemParametersInfo(SPI_SCREENSAVERRUN*NING, 1, nil, 0) then Exit;

IF LockMode=lmInput then //locking keyb and mouse
if FuncAvail(''USER32.DLL'', ''BlockInput'', @xBlockInput) then xBlockInput(true)
else Exit;

If LockMode = lmBoth then
begin
IF not SystemParametersInfo(SPI_SCREENSAVERRUN*NING, 1, nil, 0) then Exit;
if FuncAvail(''USER32.DLL'', ''BlockInput'', @xBlockInput) then xBlockInput(true)
else Exit;
end;

Result := True;
end;

Function UnLockSystem(UnLockMode:TLockMode):Bool*ean;
begin
Result:=False;

IF UnLockMode = lmSystemKeys then //UnLocking system
IF not SystemParametersInfo(SPI_SCREENSAVERRUN*NING, 0, nil, 0) then Exit;

IF UnLockMode=lmInput then //unlocking keyb and mouse
if FuncAvail(''USER32.DLL'', ''BlockInput'', @xBlockInput) then xBlockInput(false)
else Exit;

IF UnLockMode=lmBoth then
begin
IF not SystemParametersInfo(SPI_SCREENSAVERRUN*NING, 0, nil, 0) then Exit;
if FuncAvail(''USER32.DLL'', ''BlockInput'', @xBlockInput) then xBlockInput(false)
else Exit;
end;

Result := True;
end;

end.