PC to/from MAC file converter

I happened to write my diploma thesis on a MAC while having a PC. The text file
format is slightly different, but convertable. The code here is able to convert
text in both ways.
It applies only for ASCII files, no Word stuff or such.

{
CommandLine : PCMAC src dst [TOMAC/TOPC]

}
{$F+}
PROGRAM PCtoMAC;



USES OPCRT;

VAR src,dst:String;
    tomac:BOOLEAN; 


PROCEDURE copy(src,dst:STRING);
VAR s,d:FILE OF BYTE;
    l:BYTE;
BEGIN
 Assign(s,src);
 Reset(s);
 Assign(d,dst);
 Rewrite(d);
 WHILE NOT EOF(s) DO
  BEGIN
   Read(s,l);
   { to mac : remove LF }
   IF (tomac) THEN
    BEGIN
     IF (l<>10) THEN
      BEGIN
       CASE l OF
	$84:l:=$8A;	{Д}
	$94:l:=$9A;	{Ф}
	$81:l:=$9F;	{Б}
	$8E:l:=$80;	{О}
	$99:l:=$85;	{Щ}
	$9A:l:=$86;	{Ъ}
       END;
       Write(d,l);
      END;
    END
   ELSE BEGIN
   { to pc : add LF }
    IF (l=13) THEN BEGIN Write(d,l); l:=10; Write(d,l); END
    ELSE
     BEGIN
      CASE l OF
       $8A:l:=$84;
       $9A:l:=$94;
       $9F:l:=$81;
       $80:l:=$8E;
       $85:l:=$99;
       $86:l:=$9A;
      END;
      Write(d,l);
     END;
   END;
  END;
 Close(s);
 Close(d);
END;
 
PROCEDURE ParaErr;
BEGIN
   Writeln('Error in Commandline : Call ''PCMAC src dst [TOMAC/TOPC]''');
   HALT;
END;

BEGIN { main }
 Writeln(' PC     <-----> MAC translator');
 Writeln(' add LF         remove LF');
 Writeln(' changes also ДФБ ');
 Writeln;
 IF (ParamCount<>3) THEN ParaErr;
 src:=ParamStr(1);
 dst:=ParamStr(2);
 IF (ParamStr(3)='TOMAC') THEN tomac:=TRUE
 ELSE IF (ParamStr(3)='TOPC') THEN tomac:=FALSE
      ELSE ParaErr;
 copy(src,dst);
END.