i := 1;
     while getc(c) <> ENDFILE do begin
             putc(xor(c, key[i]));
             i := i mod keylen + 1
     end

Program Crypt ;
{
	Crypt -- encrypt and decrypt
}
var
	Key      :  String ;
	KeyLen   :  Byte ;...

Program Ekho ;
{
   echo command line arguments to output.
}
Uses
   Tools ;
Var
   i  :  Byte ;
begin
   for i := 0 to ParamCount do
      Write (ParamStr(i), BLANK) ;
   WriteLn
end.

c:\pascal\tools\ekho
C:\PASCAL\TOOLS\EKHO.EXE

      Function RTrim (Var S : String) : String ;
      {
         RTrim -- remove trailing blanks
      }
      Var
         i : Byte ;
      begin { RTrim }
         for i := Length(S) downto 1 do
            if S[i] > BLANK then begin
               S     := Copy(S,1,i) ;
               RTrim := S ;
               Exit
            end ;
         {
               if we reach this point then S contains only BLANKS
            so we return a null string
         }
         S     := '' ;
         RTrim := S
      end ; { RTrim }

      Function LTrim (Var S : String) : String ;
      {
         LTrim -- remove leading blanks
      }
      Var
         i : Byte ;
      begin { LTrim }
         for i := 1 to Length(S) do
            if S[i] > BLANK then begin
               S     := Copy(S,i,MAXSTR) ;...

{
PROGRAM
      DeTab    -- convert tabs to blanks
USAGE
      DeTab
FUNCTION
      DeTab copies its input to its output, expanding horizontal tabs to 
      blanks along the way, so that the output is visually the same as the        
      input, but contains no tab chars.  Tab stops are assumed to be set
      every three columns (i.e., 1, 4, 7, 10, ...), so that each tab char
      is replaced by from one to three blanks.
BUGS
      1. DeTab is naive about backspace, vertical motions, and
         non-printing chars.
      2. Each line of output will be truncated at MAXSTR chars.
      3. Trailing BLANKS will be trimmed from each line of output.
}

PROGRAM
   EnTab -- convert runs of blanks into tabs
USAGE
   EnTab
FUNCTION
   EnTab copies its input to its output, replacing strings of blanks by
   tabs so that the output is visually the same as the input but contains
   fewer characters.  Tab stops are assumed to be set every 3 columns
   (i.e., 1, 4, 7, ...), so that each sequence of one to four blanks
   ending on a tab stop is replaced by a tab character.
BUGS
   1. EnTab is naive about backspaces, vertical motions and non-printing
      characters.
   2. EnTab will convert a single blank to a tab if it occurs at a tab
      stop, thus EnTab is not an exact inverse of DeTab.
   3. if any record in the input is longer than 255 char Entab will
      truncate that record to 255 char.

Program ShowTabs ;
{
ShowTabs -- display tabs in a file.
}
Uses
    Tools ;	{ TAB and CARET ( ^ )}
Var
    Ch :  Char ;
begin { ShowTabs }
    while NOT eof do begin
        Read (Ch) ;
        if Ch = TAB then
            Ch := CARET ;
        Write (Ch)
    end
end.  { ShowTabs }

...

Program Ascii ;
{
   outputs all the ascii chars ... maybe
}
Var
   i  : Byte ;
begin { Ascii }
   for i := 0 to 127 do
      Write (Chr(i))
end.  { Ascii }

ascii > ascii.all
type ascii.all

Program LineCnt ;
{
      count lines in standard input
}
Var
   Count : LongInt ;
begin { LineCnt }
   Count := 0 ;	
   while NOT eof do begin
      ReadLn ;
      Count := Count + 1
   end ;
   WriteLn (Count:0)
end.  { LineCnt }

Count := 0

Program CharCnt ;
{
      count characters in standard input
}
Var
   Count : LongInt ;
   Ch    : Char ;
begin { CharCnt }
   Count := 0 ;
   while NOT eof do begin
      Read (Ch) ;
      Count := Count + 1
   end ;
   WriteLn (Count:0)
end.  { CharCnt }  

Now is the time for all good men
Now is the time for all good men
to come to the aid of their country.
to come to the aid of their country.
^Z

Kopy < kopy.pas > kopy.txt

fc kopy.pas kopy.txt

type
	character = -1..127;   { ASCII, plus ENDFILE }

const
	ENDFILE = -1;
	NEWLINE = 10;	{ ASCII value }

...