{$M 4000, 0, 0}

program ATOM046C { tests access to $40:$6c } {$IFNDEF MSDOS} Fail {$ENDIF} ;

uses Dos ;

var head : word absolute $40:$1A ;
    tail : word absolute $40:$1C ;


procedure FlushKB ; begin head := tail end { TSFAQP #16 } ;


function KeyPressed : boolean { without Crt } ;
begin KeyPressed := head<>tail end ;


procedure TestProc ;
var N, S, T : longint ; Timer : longint absolute $40:$6C ;
begin N := 0 ; S := 0 ;
  repeat Inc(S) ; Timer := $0000FFFF ;
    repeat if KeyPressed then EXIT ;
      Inc(N) ; T := Timer ;
      if (T<>$0000FFFF) and (T<>$00010000) then
        Writeln('Loop # ', N,
        ', Ticks tested ', S, ', Timer read ', T, ' = fail') ;
      until T<>$0000FFFF ;
    until false ;
  end {TestProc} ;


BEGIN Writeln('ATOM046C.PAS  www.merlyn.demon.co.uk  >= 2000/02/26') ;
Writeln(' See http://www.merlyn.demon.co.uk/pas-time.htm') ;
Writeln(' Not intended for use in a Window.') ;
Writeln(' Press any key to terminate test :') ;
TestProc ;
FlushKB ;
SwapVectors ;
Exec(GetEnv('COMSPEC'), '/C TIME') ;
SwapVectors ;

{ This reads $40:$6C non-atomically when compiled with BP7
  (as Borland compiles longint access as two word accesses),
  as shown by the readings of 131071; but not shown in TP5. }

END.