ORIGINAL DOC
                            
  Update history:
 
  1/1/88 - Frank da Cruz.  Add exit(0); to end of main() to give good
  return code upon success.
 
  Modified 3/11/86 Howie Kaye -- Columbia University
  added UNIX and Microsoft C compatibility
  changed I/O to be buffered
  note: there is a bug built into the EOF handling which causes the
  output file to grow everytime a file is packed/unpacked.  This is
  because 2 nulls and a space are added at the end of each run.  As
  the data is past the end of the file, it does not affect the program
  produced.
 
  [1]	 Version adapted from the DEC-20 code to run on Lattice-C (v 2.14)
  on an IBM PC/AT under DOS 3.0.  Alan Phillips, Lancaster University UK
 
  Original by Bill Catchings, Columbia University, July 1984

 

  This program takes a file and encodes it into printable characters.
  These printable files can then be decoded by the programs MSPCBOOT.BAS
  or MSPCTRAN.BAS as the need may be.	The file is encoded by taking
  three consecutive eight bit bytes and dividing them into four six bit
  bytes.  An ASCII zero was then added to the resulting four characters.
  to make them all printable ASCII characters in the range of the
  character zero to the character underscore.	In order to reduce the
  size of the file null repeat count was used.  The null repeat count
  compresses up to 78 consecutive nulls into only two characters.  This
  is done by using the character tilde (~) as an indication that a group
  of repetitive nulls has occured.  The character following the tilde is
  number of nulls in the group.  The number is also converted in to a
  printable character by adding an ASCII zero.  The highest number of
  nulls is therefore the highest printable character tilde.  This is
  equal to tilde minus zero nulls or 78 nulls.  Because of the three
  byte to four byte encoding the repeat counting can only start with
  the first character of a three byte triplet.
 
  This C program was written specifically for the DEC-20 and as such
  will not easily be transported to another system.  The main problem
  lies in the file I/O routines.  It is necessary to make sure that
  untranslated eight bit bytes are input from the input file.	The
  main change would be to make the OPEN statement reflect this for
  your particular system and brand of UNIX and C.  The rest of the
  program should be transportable with little or no problems.