Here is general pseudo code for the control program (rough draft)

                    Main Program Pseudo Code

Initialize. This is complicated but will result in the board being loaded and the current player being logged in.

Report referee calls made to opponent

do
  Get LegalMove
  - Checkmate or resign? goto TheEnd
loop until legal move made

Save for possible file transfer via email, etc.

Exit (Other player gets file and starts program)

TheEnd:

Display board (both player's pieces)

Exit

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GetLegalMove:

Move=DisplayBoard ("White" or "Black") (SHARED Board unchanged)

Select case LegalMove(Move)
Case 0:
  announce "Not possible" to player
  record that was said
  return indicating no legal move found
Case 1:
  announce "Illegal" to player
  (don't record that)
  return indicating no legal move found
Case 2
  move piece on SHARED board
  (remembering en passent, king and rook)
  return indicating legal move made