17652 Wellington Ave.
                                          Tustin, CA 92680

                                          February 3, 1988

         PC-SIG
         1030D East Duane Avenue
         Sunnyvale, CA 94086


         Gentlemen:

         I am submitting the enclosed program entitled "Silicon Sky" 
         for distribution as "Shareware".  The requested registration 
         fee is $10.00.  Silicon Sky is an astronomy program which 
         displays approximately 1600 stars as seen from any latitude 
         on earth for a selected date, time and direction of 
         observation. In addition the program displays the location of 
         the sun, moon and planets and shows the correct phase of the 
         moon.  More detailed technical data giving coordinates of 
         solar system objects can be displayed by selecting the proper 
         option from the on-screen menu.  Finally, it identifies the 
         constellations visible on the screen by marking out their 
         boundaries. 

         The program requires an IBM or compatible with a color 
         graphics card (CGA) or an enhanced graphics card (EGA).  An 
         8087 math co-processor chip is supported and speeds up 
         execution time considerably, especially when compared to a 
         standard PC without the chip.  The contents of the individual 
         files are as follow:
         
               SISKY.EXE    The main program for machines without 8087 chip
               SISKY87.EXE  The main program for machines with 8087 chip
               INIT.EXE     Initialization program for non 8087 machines
               INIT87.EXE   Initialization program for 8087 machines
               SISKY.XYZ    Coordinate data for 1600 stars
               SISKY.CLR    File with initialization data
               SISKY.HRZ    Horizon for sky display
               SISKY.DME    Top of celestial sphere for sky display
               SISKY.CNM    Name and central coordinates for constellations
               READ.ME      Text file with program instructions 
               LETTER.TXT   Text file with this letter    
               ARIES...VOLANS  These thirty five files contain 
                               boundary data for each constellation


         Sincerely,


         Larry Adkins