program ReadKbrd;
 const kbrd = 35; {keyboard unit number}
       ControlZ = $1A;
       ControlA = $01;
       ok = false;
 var ch : -128..127;
     keypress : boolean;
     fourbytes : longint;
     i,SendRaw : integer;

 procedure display;
  const bs = $08; {back space}
        lf = $0A; {line feed}
        cr = $0D; {carriage return}
        tab = $09; {tab}
        esc = $1B; {escape}
        bell = $07; {bell}
  var ch1 : -128..127;

  Begin
    if (ch>=0) and (ch<=$1F) and (NOT(ch in [bell,bs,lf,cr])) then {control character}
      if ch=esc then write('|Esc|')
      else if ch=tab then write('           ')  {tab=10 spaces}
           else write('^',chr(ch+$40))
    else if ch<0 then begin
            ch1 := ch+128;
            if (ch1>=0) and (ch1<=$1F) then write('|alt-^',chr(ch1+$40),'|')
                                     else write('|alt-',chr(ch1),'|');
         end else write(chr(ch));
  End; {display}

BEGIN
 SendRaw := 0;
 writeln;
 writeln('Echo character input from key board.');
 writeln('Press CONTROL-Z to stop.  Do this by pressing the "CTRL" ');
 writeln('   and  "Z" keys together.');
 writeln;

 repeat
   if ok then write('- DOING UNITBUSY -');
   keypress := unitbusy(kbrd);
   if keypress then begin
      if ok then begin
         for i:= 1 to 1000 do;
         write('- DOING 2ND UNITBUSY -');
         keypress := unitbusy(kbrd) (*  TRUE *);
         if keypress then begin
            write('- DOING UNITREAD -');
            unitread(kbrd,ch,1);
            display;
         end else ch := 0;
      end else begin
         unitread(kbrd,ch,1);
         display;
      end;

      if ch=ControlA then begin
          SendRaw := 1-SendRaw; {invert}
          unitstatus(kbrd,SendRaw,0); {change send raw}
      end;

   end else ch := 0;

 until(ch=ControlZ);
 writeln;
END.