L I N E W A R S   Version 1.xx  
                       Made in Finland by Patrick Aalto  

      Technical Information
      
        LineWars is compiled with Turbo Pascal 5.0 (currently 1000 lines)  
      and  Microsoft  Macro Assembler 4.0  (very many lines).  The source
      code takes about 400KB of disk storage.  LineWars is constructed as
      a  Pascal main program having various Assembler units to call.  The
      whole graphical game is one unit.
      
      Initial Procedures  

        When LineWars is started, it first checks that you really do have
      an EGA card.  It does this by checking that EGA ROM BIOS at address
      C000h:001Eh...0020h contains letters 'IBM'.  If not, the program is 
      terminated to prevent possible damage on your non-EGA display. When
      LineWarC is started, this check is not used.
      
        After that check  LineWars reads in  the settings-file.  It first
      checks the command line parameters and reads the file mentioned, if
      it exists.  If not,  default settings are used.  If no command line
      parameters are given,  LineWars tries to read  a file LINEWARS.SET.
      If it cannot be found, again default settings are used.
      
        When settings are read in,  LineWars takes posession of  a RS-232
      line and it's interrupts.  It does this whether War Mode is Duel or
      Single. If Baudrate is not 'Check',  LineWars also changes the baud
      rate of the appropriate com port.
      
        After that the current screen contents are saved and Main menu is
      shown. If Connect Mode is 'BBS-"door"', LineWars sends it's logo to
      communications line. Cursor is also made hidden now.
      
        While in Main Menu,  the line is constantly monitored to check if
      we received an order to play ('î' = ascii 238) or to start terminal
      ('ì' = ascii 236) or,  if 'BBS-"door",  a request to quit (ctrl-X).
      If none of these is received, LineWars checks if the user requested
      an action. If so, that action is taken. If the action was Terminal,
      an ascii 236 is sent to line, and if the action was 'quit',  ctrl-X
      is sent, unless in BBS-"door" mode,  when ascii 236 is sent to make
      the other side start terminal mode and receive 'LineWars quitting'-
      texts.
      
        If Play is selected, then  EGA / CGA appropriate graphics mode is
      selected and the Cobra IV cockpit drawn on the screen.  If War Mode
      is Duel,  LineWars shows a 'wait for connection'-message and begins
      to wait for incoming 'î'. If one is not received within half a sec,
      'î' is sent to line. This repeats until 'î' is received or the user
      presses ESC. After a succesfull connection,  LineWars sends to line
      your codename  plus information whether your Key Damp is on or off.
      It then tries to receive that information.  When this is done,  the
      game starts.
      
        When in game,  first the  keyboard interrupt is changed to make a
      distinction between control- and letter keys.  Then all meters  are
      drawn,  the MainViewer opened  and the line begins to transfer info
      about which keys the user presses.
      
        After your shield energy is totally exhausted, your computer will
      say 'Ouch, that hurts' and your opponent will see your ship explode.
      The human voice  is part of  a digitized speech demo  I came across
      while developing the game.  I think it sounds pretty nice,  but you
      may disagree.  You cannot turn it off,  however.  There is a chance
      that this speech procedure will hang a  4.77 Mhz machine,  but then
      again who still has such a machine? (with EGA!) :-)  That digitized
      speech,  together with  the procedure to drive speaker,  takes less 
      than 2 Kbytes of code, by the way.      
      
      Line Protocol
        
        When in actual battle,  LineWars sends and receives  one byte per
      every new frame.  That means  the line must be able  to transfer 18
      characters per second if the Framerate is 18Hz. This is because the
      game needs to be synchronized between two machines running possibly 
      at different speeds. If you press a letter-key (or <Ù or BACKSPACE)
      it  will be sent  between two synchronizing bytes  so that the line
      should actually be able to transfer about 30 bytes/sec. at maximum.
      
        The transferred bytes are coded as follows:
        
       7 6 5 4 3 2 1 0  = bit position  
      ÚÄÂÄÂÄÂÄÂÄÂÄÂÄÂÄ¿   
      ³0³?³1³?³?³?³?³?³ = Any non-control character (ascii 32..127)  
      ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´   
      ³1³0³L³R³U³D³x³x³ = Left/Right/Up/Down -key pressed. x = Not used.  
      ÃÄÅÄÅÄÅÄÅÄÅÄÅÄÅÄ´   
      ³1³1³L³M³D³I³E³x³ = Laser Fired/Missile Fired/Decrease Speed/  
      ÀÄÁÄÁÄÁÄÁÄÁÄÁÄÁÄÙ   Increase Speed/Enemy Exploded.
      
      If no key is pressed, ascii code 128 is sent. In addition to those,
      ascii codes 13 and 8 are used for sending RETURN and BACKSPACE.  
          
        As you can see,  only the  most important information  is passed.
      This may result into very different environments  at different ends
      of the line,  but usually one battle  does not last long enough for
      this to be notable.  Possible line errors may  corrupt  or stop the
      game from running.  If this happens,  just press ESC, wait a little 
      while and try the game gain.  Future versions of LineWars  will use
      a line checking method.