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╨╟═-64 ╨ROGRAM ╟RAPHICS ═ANAGEMENT ON THE ├OMMODORE 64 ┬Y ─AVID ╨. ─ARUS, ╦EN ╞RENCH, AND ╠OUIS ╥. ╫ALLACE ╧RIGINALLY PUBLISHED IN ├OMMODORE ╨OWER/╨LAY -- ╞EBRUARY/═ARCH 1986 ╧╓┼╥╓╔┼╫ OF ╨╟═-64 ------------------ ╚AVE YOU EVER BEEN WRITING A ┬┴╙╔├ PROGRAM THAT USES SOME PART OF THE ├OMMODORE 64'S GRAPHICS ONLY TO FIND THE PROGRAM RUNS TOO SLOW? ╩UST TO PLOT A POINT REQUIRES SEVERAL LINES OF PROGRAM. ┴NIMATING SPRITES USING ╨╧╦┼'S REDUCES THEIR MOTION TO A CRAWL. ┘OUR ALTERNATIVES ARE TO WRITE IN MACHINE LANGUAGE OR USE A ┬┴╙╔├ LANGUAGE EXTENSION. "╨╟═-64" GIVES YOU THE BEST OF BOTH THOSE ALTERNATIVES. ╨╟═, WHICH STANDS FOR ╨ROGRAM ╟RAPHICS ═ANAGER, IS A LIBRARY OF VERY FAST MACHINE-LANGUAGE SUBROUTINES THAT YOU USE LIKE ┬┴╙╔├ COMMANDS. ╘HIS SYSTEM ALLOWS YOU TO USE THE HIGH-RESOLUTION GRAPHICS AND ANIMATION OF THE ├OMMODORE 64 WITHOUT ┬┴╙╔├'S SPEED LIMITATIONS, AND ALSO HAVE THE USE OF THE ╥┴═ HIDDEN UNDER THE OPERATING SYSTEM. ╧NE OF THE MANY POWERFUL FEATURES OF ╨╟═ IS THE APPROACH TO CHARACTER GRAPHICS. ╚ERE, THERE IS NO SEPARATE TEXT MODE OR GRAPHICS MODE. ╔N MANY WAYS, THIS IS THE WAY THE ┴PPLE ═ACINTOSH WORKS; AND, IN FACT, THERE ARE STRONG SIMILARITIES BETWEEN THE ═AC AND ╨╟═'S GRAPHIC ABILITIES. ╠IKE THE ═ACINTOSH, ╨╟═ ALLOWS YOU TO FREELY MIX TEXT AND GRAPHICS ON THE SAME SCREEN. ┘OU CAN HAVE AS MANY DIFFERENT TEXT STYLES AS YOU WISH. ╘EXT CAN BE ENLARGED TO DOUBLE HEIGHT OR DOUBLE WIDTH OR BOTH. ╨╟═ ALSO SUPPORTS 80-COLUMN REGULAR AND DOUBLE-HEIGHT GRAPHICS. ╘HE CHARACTERS CAN BE IN ANY OF 16 COLORS, AND EACH CHARACTER'S BACKGROUND COLOR CAN BE INDEPENDENTLY CONTROLLED JUST AS IN ┼XTENDED ├OLOR ╘EXT ═ODE. ┼ACH CHARACTER STRING CAN BE PRINTED AT SPECIFIC SCREEN LOCATIONS, GIVING YOU A VERY EFFECTIVE ╨╥╔╬╘ ┴╘ COMMAND. ╨╟═ ALSO ALLOWS YOU TO EASILY PLOT POINTS, DRAW LINES, AND FILL AN AREA IN ANY COLOR YOU WISH, SO YOU CAN INTERMIX YOUR NEW TEXT GRAPHICS WITH BITMAP DISPLAYS LIKE CHARTS AND DRAWINGS. ╞OR THOSE OF YOU INTERESTED IN GRAPHING DATA, A 3─ ┬┴╥ COMMAND IS INCLUDED. ╘O MAKE 3─ BARS, JUST GIVE THE SIZE, COLOR AND LOCATION, AND THEY QUICKLY GROW ON THE SCREEN. ╘HIS IS GREAT FOR COMBINING TEXT AND BITMAP IMAGES IN COLORFUL PRESENTATION-QUALITY GRAPHIC DISPLAYS. ╒SING ╨╟═, YOU CAN EVEN EMULATE WINDOWS IN YOUR PROGRAMS. ╫INDOWS ARE SUB-SCREENS WITHIN THE MAIN SCREEN, AND CAN BE ANY SIZE FROM A FULL SCREEN TO A SINGLE CHARACTER. ┘OU CAN EASILY SUPERIMPOSE ONE IMAGE ON ANOTHER (FOR INSTANCE, SUPERIMPOSE A GRAPH ON TOP OF A SPREADSHEET), MANIPULATE IT, AND THEN RESTORE THE ORIGINAL UNDERNEATH. ╧R MAYBE YOU WANT TO GET A DIRECTORY, PRINT IT ON THE SCREEN IN A WINDOW, AND THEN POP THE WINDOW BACK UP WITHOUT EFFECTING WHAT'S UNDER IT. ╞IVE NEW COMMANDS ARE PRESENT SO YOU CAN COPY A WINDOW, RESTORE IT, FILL IT WITH A VALUE, REVERSE IT, OR EVEN COLOR IT. ╫HEN YOU USE THE WINDOW-COPY COMMAND, YOU MUST HAVE A SECTION OF MEMORY SET ASIDE FOR IT TO BE STORED. ╘HERE ARE A NUMBER OF PLACES IN THE 64 WHERE FREE ╥┴═ IS AVAILABLE TO DO JUST THAT. ╞OR INSTANCE, THERE IS 8╦ OF ╥┴═ UNDER ┬┴╙╔├ (40960-53247) AND THERE IS ANOTHER 8╦ UNDER THE KERNAL (57344-65343). ╘HERE IS ALSO 4╦ OF ╥┴═ AT $├000 (49152-53247) AND ANOTHER 195 BYTES IN THE CASSETTE BUFFER (828-1023). ╘HIS GIVES OVER 20╦ OF ADDITIONAL ╥┴═ FOR YOU TO USE AS SCREENS AND STORAGE AREAS. ╘O ACCESS THESE AREAS, THERE ARE SEVERAL MEMORY MANAGEMENT COMMANDS, INCLUDING THE ╙┼╘ ┴──╥┼╙╙ AND ╪╞┼╥ ═┼═╧╥┘ COMMANDS. ╙PRITES (MOVEABLE OBJECT BLOCKS) ARE AN IMPORTANT FEATURE OF THE ├OMMODORE 64. ╨╟═ FULLY SUPPORTS SPRITES WITH OVER A DOZEN COMMANDS, INCLUDING ONE THAT ALLOWS YOU TO USE A JOYSTICK OR THE CURSOR KEYS TO CONTROL AN ICON SPRITE IN MUCH THE SAME WAY AS THE ═ACINTOSH'S MOUSE IS USED. ╬O PROGRAMMING IS REQUIRED TO MOVE THE ICON ONCE IT HAS BEEN ACTIVATED. ╔N ADDITION, ╨╟═ PROVIDES A ╙╨╥╔╘┼ ┴╬╔═┴╘┼ COMMAND. ┴NIMATE ALLOWS THE ┬┴╙╔├ PROGRAMMER TO TELL A SPRITE TO GO FROM ITS CURRENT POSITION TO A GIVEN X AND Y AT A SPECIFIED SPEED. ╘HE SPRITE IMMEDIATELY BEGINS TO MOVE, WHILE ┬┴╙╔├ IS FREE TO PROCESS OTHER COMMANDS. ╙PRITES CAN ALSO BE INTERNALLY ANIMATED BY CHANGING THE POINTER TO THE DATA THAT DESCRIBES THEIR FORM. ╔F ╙PRITE ┴NIMATE ISN'T ENOUGH, THERE IS ANOTHER SPRITE MODE AVAILABLE TO ╨╟═ USERS: 14-╙╨╥╔╘┼ MODE. ╘HIS USES MORE INTERRUPT PROGRAMMING TECHNIQUES TO GIVE YOU AN ADDITIONAL SIX SPRITES. ╘HE PROGRAM TITLED ╨╟═.┬╔╬ IS THE MACHINE LANGUAGE THAT MAKES UP THE ╨╟═ SYSTEM. ╘HE PROGRAM TITLED ╨╟═ IS THE ┬┴╙╔├ LOADER WHICH LOADS ╨╟═.┬╔╬ ONTO MEMORY AND INITIALIZES THE ╨╟═ SYSTEM. ╘HE FILE ├╚┴╥ ╙┼╘╙ CONTAINS THE 80 COLUMN AND OTHER CHARACTER SETS. ╘HESE ARE THE MINIMUM SYSTEM. ╙EVERAL DEMONSTRATION PROGRAMS AND THEIR ASSOCIATED DATA FILES ARE ALSO PROVIDED. ╘HERE ARE A TOTAL OF 41 COMMAND IN ╨╟═. ╘O GET THE RIGHT RESULTS, YOU MUST BE CAREFUL TO USE THE CORRECT SYNTAX. ╙OME OF THE PARAMETERS ARE OPTIONAL AND CAN BE OMITTED IF NOT NEEDED. ╘HESE OPTIONAL PARAMETERS ARE ENCLOSED IN BRACKETS IN THE FOLLOWING PROGRAMMERS' DOCUMENTATION. ╘HOSE PARAMETERS NOT ENCLOSED WITH BRACKETS ARE REQUIRED. ╨╟═ ╘IPS -------- 1. ╘HE PROGRAM DOES NOT SUPPORT TAPE OR ╥╙232. 2. ┬E SURE TO SAVE THE PROGRAMS YOU WRITE BEFORE YOU RUN THEM. 3. ┴LWAYS ENTER AND EXIT 14-SPRITE MODE AS DESCRIBED IN THE ├OMMAND SUMMARY FOLLOWING THIS SECTION. 4. ┬E CAREFUL WITH YOUR MEMORY MANAGEMENT. ╘RYING TO WRITE OUTSIDE OF THE AVAILABLE ╥┴═ AREAS (SEE ═EMORY ═AP) WILL CAUSE THE COMPUTER TO CRASH. 5. ╙TRANGE EFFECTS CAN BE ACHIEVED WHEN MOVING SPRITES ACROSS THE SCANLINE BOUNDARY. ╘HESE MAY BE USEFUL IN CERTAIN SITUATIONS. 6. ╘HE FIRST LINES OF ANY PROGRAM SHOULD BE: 10 ╔╞ ┴=0 ╘╚┼╬ ┴=1:╠╧┴─ "╨╟═",8,1:╥┼═ ╠╧┴─ ╨╟═ 20 ╨╧╦┼ 55,255:╨╧╦┼ 56,131:├╠╥:╥┼═ ╠╧╫┼╥ ╘╧╨ ╧╞ ┬┴╙╔├ ┬┼╠╧╫ ╨╟═ 30 ┬┴=33792:╥┼═ ─┼╞╔╬┼ ┬┴╙┼ ┴──╥┼╙╙ 40 ╙┘╙ ┬┴+6,╚╔╥┼╙ ┴──╥┼╙╙, ├╧╠╧╥ ═┼═╧╥┘:╥┼═ ╙┼╘ ┴──╥┼╙╙ 50 ╙┘╙ ┬┴:╥┼═ ┴├╘╔╓┴╘┼ ╨╟═ 60 ╙┘╙ ┬┴+24:╥┼═ ┼╬╘┼╥ ╚╔╥┼╙ ═╧─┼ 7. ┼ND YOUR PROGRAM WITH: 10000 ╙┘╙ ┬┴+27:╙┘╙ ┬┴+3:┼╬─:╥┼═ ╚╔╥┼╙ ╧╞╞, ╨╟═ ─┼┴├╘╔╓┴╘┼─ ╔F YOUR PROGRAM STOPS AND YOU SUSPECT IT HAS HIT A SYNTAX ERROR, TRY TYPING ╟╧╘╧ 100000. ╘HIS WILL GET YOU OUT OF ╨╟═ AND YOU CAN CHECK FOR ERROR MESSAGES ON THE TEXT SCREEN. 8. ╞OR THE MOST EFFICIENT USE OF YOUR MEMORY, WE RECOMMEND YOU USE 57344 AS YOUR BITMAP SCREEN AND 52224 AS YOUR COLOR MEMORY. ╘HIS ALLOWS THE ╥┴═ AT 40960-52223 TO BE USED FOR STORAGE OF CHARACTER SETS, SCREENS, WINDOWS AND SPRITES. 9. ┴LL VALUES FOR PARAMETERS ARE IN DECIMAL. 10. ┴RRAYS CAN BE USED IN PARAMETERS. ╫HEN USING WINDOWS, KEEP IN MIND THAT IT IS UP TO YOU TO HANDLE THE MEMORY MANAGEMENT. ╨╟═ WILL WRITE OR READ TO ANY AREA YOU TELL IT AND IF YOU ARE NOT CAREFUL, THE RESULTS ARE UNPREDICTABLE. ╞OR EXAMPLE, WHEN YOU WANT TO STORE A GIVEN AREA AS A WINDOW, YOU MUST KNOW HOW MUCH MEMORY IT WILL TAKE TO STORE A WINDOW OF ITS SIZE IN ORDER TO KNOW WHERE IT CAN BE STORED. ╔F YOUR WINDOW IS TEN ROWS BY TEN COLUMNS, THAT EQUALS 100 CHARACTER-SIZE BLOCKS OF ╥┴═. ┼ACH CHARACTER BLOCK HAS EIGHT BYTES OF ╥┴═ FOR BITMAP AND ONE BYTE FOR COLOR MEMORY. ╙O A TEN-BY-TEN WINDOW REQUIRES 900 BYTES PLUS TWO BYTES OVERHEAD, FOR A TOTAL OF 902 BYTES. (╘HE TWO-BYTE OVERHEAD IS ALWAYS THE SAME, REGARDLESS OF WINDOW SIZE.) ┘OU CAN FIND THE ADDRESS OF THE LAST BYTE OF MEMORY USED BY CODING THE PROCEDURE GIVEN UNDER THE ├╧╨┘ ╫╔╬─╧╫ COMMAND. ╫HEN YOU WANT TO RESTORE A COPIED WINDOW, USE THE ╥┼╙╘╧╥┼ ╫╔╬─╧╫ COMMAND WITH THE ADDRESS OF THE AREA OF ╥┴═ WHERE THE STORED WINDOW BEGINS, AND THE ROW AND COLUMN TO WRITE IT BACK TO. ╔T WILL BE RESTORED (WITH COLOR) TO THE SPECIFIED AREA OF THE SCREEN. ╘HE SPRITE COMMANDS OFTEN REQUIRE SPRITE POINTERS. ┴ SPRITE POINTER IS A NUMBER THAT INDICATES WHERE IN MEMORY THE FIRST BYTE OF SPRITE DATA IS LOCATED. ╘HE ╙╨╥╔╘┼ ╨╠╧╘ AND ┴╬╔═┴╘┼ COMMANDS BOTH USE SPRITE POINTERS IN THE RANGE OF 0-255. ╘HE SPRITE DATA MUST BE WITHIN THE 16╦ BANK OF MEMORY YOU HAVE SET YOUR SCREENS AT USING THE ╙┼╘ ┴──╥┼╙╙ COMMAND. ╞OR INSTANCE, IF YOUR SCREEN IS AT 57344, ALL SPRITE DATA MUST BE WITHIN THE AREA OF 49152-65535. ┴ SPRITE DESCRIPTION STORED AT 49152 HAS A POINTER VALUE OF ZERO, WHILE ONE AT 49216 (49152+64) HAS A POINTER VALUE OF ONE. ╙O POINTER ZERO BEGINS AT THE FIRST ADDRESS OF THE VIDEO BANK YOU ARE IN, WHILE POINTER 255 LIES AT THE END OF THE 16╦ VIDEO BANK YOU ARE IN. ╥EMEMBER THAT THE SPRITES MUST BE STORED IN THE SAME BANK AS YOUR SCREEN WHEN YOU WANT TO USE THEM. ╚OWEVER, SEVERAL SPRITE UTILITY COMMANDS (╙╨╥╔╘┼ ╥┼╞╠┼├╘, ╙╨╥╔╘┼ ╥┼╓┼╥╙┼ AND ╙╨╥╔╘┼ ╪╞┼╥ USE POINTERS IN THE RANGE OF 0-1023. ╘HE DIFFERENCE HERE IS THESE COMMANDS ARE NOT USED TO VISUALIZE SPRITES, BUT INSTEAD ARE SPECIAL WAYS OF HANDLING SPRITE DATA IN MEMORY. ╘HIS IS ONLY THEORETICAL, SINCE SOME OF THESE POTENTIAL LOCATIONS ARE IN USE BY THE COMPUTER (╙EE ═EMORY ═AP). ┬Y USING THESE POINTERS, YOU CAN MANIPULATE SPRITE DATA WITH THESE SPRITE UTILITIES. ╞OR INSTANCE, SUPPOSE YOUR SCREEN IS AT 57344, WHICH MEANS THE VIDEO CHIP IS LOOKING AT LOCATIONS 49152-65535. ┴LL SPRITES MUST BE LOCATED SOMEWHERE WITHIN THIS AREA TO BE SEEN. ╚OWEVER, THE SPRITES YOU ARE NOT USING AT THE TIME CAN BE STORED SOMEWHERE ELSE, LIKE UNDER ┬┴╙╔├ ╥╧═ AT 40960. ╫HEN THE TIME COMES FOR YOU TO USE THOSE STORED SPRITES, THE ╙╨╥╔╘┼ ╪╞┼╥ COMMAND CAN BE USED TO TRANSFER THEM FROM THEIR TEMPORARY STORAGE TO SOMEWHERE IN THE ACTIVE VIDEO BANK. ╚ERE IS AN EXAMPLE OF THE ╙╨╥╔╘┼ ╪╞┼╥ COMMAND: ╙┘╙ ┬┴+96,512,10,767 ╔T SAYS TO TRANSFER THE SPRITES STARTING AT ABSOLUTE SPRITE POINTER 512 (40960 DECIMAL) AND TAKE TEN OF THEM (10*64 BYTES) AND PUT THEM AT ABSOLUTE POINTER 767 (49152). ╚ERE THE SPRITE POINTER OF 49152 IS 767, NOT ZERO, AS IT WOULD BE IF YOU WERE MOVING OR ANIMATING A SPRITE. ╒SER ═EMORY ═AP --------------- 0-255 ╬OT AVAILABLE 251-254 ╞REE ZERO PAGE 255-827 ╬OT AVAILABLE 828-1023 ╞REE ╥┴═ 1024-2047 ╬ORMAL LOW-RES SCREEN 2048-33791 ┬┴╙╔├ ╥┴═ 33792-40959 ╨╟═ SYSTEM 40960-53247 ╞REE ╥┴═ 53248-57343 ╬OT AVAILABLE 57344-65343 ╞REE ╥┴═ 65344-65535 ╬OT AVAILABLE ╘HIS FILE WAS PAINSTAKINGLY TYPED IN BY ╘HE ╙HARK! FROM THE ╨╟═ ARTICLE IN THE ╞EB./═ARCH 1986 ├OMMODORE ╨OWER/╨LAY MAGAZINE BY ─AVID ╨. ─ARUS, ╦EN ╞RENCH, AND ╠OUIS ╥. ╫ALLACE. ╘HE PROGRAM HAS BEEN GRACIOUSLY PLACED IN THE PUBLIC DOMAIN BY THE AUTHORS. ╞OR A COMPLETE LIST OF ╨╟═-64 COMMAND SYNTAX, SEE ╨╟═ ├╧══┴╬─╙.─╧├.