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Text File | 1990-02-12 | 37.0 KB | 781 lines

╘ITLE ╙CREEN ┬ACK╟ROUND ----------------------- ╘HE TITLE SCREEN ╔ ENVISONED AS A BORDERED SCREEN (USING THE NORMAL ├= CHARACTER SET - IE: ├= ┴,╙,┌,╪ ON THE KEYBOARD) WITH OUR BITMAP IN THE MIDDLE AND UNDER-NEATH IT A SHORT DESCRIPTION OF THE GAME AND GAME-PLAY INSTRUCTIONS. ╬OW THIS IS MY IDEA OF THE SCREEN LAYOUT (ROUGH DRAWING AS WE'RE NOT USING THE ACTUAL SCREEN DIMENSIONS): +-------------------------------------------------------------+ ▄ -╠╧╟╧ ----------------------------------------------------- ▄ ▄ --------------X 3 LINES------------------------------------ ▄ ▄ ----------------------------------------------------------- ▄ ▄ ▄ ▄ ╙PACE ╔NVASION ├64/128 ▄ ▄ ╨ROGRAMMING : ├RAIG ╘AYLOR ▄ ▄ ╟RAPHICS : ╨ASI ╧JALA ▄ ▄ ╙OUND : ???????????? ▄ ▄ ▄ ▄ ----------------------------------------------------------- ▄ ▄ ╘O ╨LAY: ▄ ▄ ╒SE JOYSTICK IN PORT 2, MOUSE IN PORT 1 OR KEYBOARD: ▄ ▄ ┴ - ╠EFT, ┌ - ╥IGHT ╙PACE - ╞IRE ▄ ▄ ╞1 - ╥ESTART ▄ ▄ ▄ +-------------------------------------------------------------+ ╘ITLE ╙CREEN ╞ORMATTING ----------------------- ╫E COME INTO A PROBLEM HERE -- THE SCREEN IS SOME 1000 CHARACTERS ON THE ├64, AND 2000 CHARACTERS FOR THE ├=128. ╔T WOULD BE EXTREMELY WASTEFUL TO STORE THAT MANY CHARACTERS IN MEMORY JUST TO REPRODUCE A TITLE SCREEN - AND MOST OF THEM CONSISTING OF SPACES AT THAT!! ╫HAT WE'LL DO IS TO JUST SPECIFY THE ADDRESS ON SCREEN, THE # OF CHARACTERS AND THEN LIST THE CHARACTERS. ╔T WILL BE SIMILAIR TO OUR CUSTOM CHARACTER TABLE DRIVER ABOVE BUT WILL BE DIFFERENT ENOUGH THAT A NEW ROUTINE IS WARRENTED. ╫E WILL HOWEVER USE THE TWO SUBROUTINES WRITEBYTE AND SETADRS THAT WERE DEVELOPED IN THE PREVIOUS ROUTINE. ╘HE DATA WILL LOOK LIKE THE FOLLOWING: .WORD ADDRESS .BYTE NUM_OF_CHARS ($00= END OF DATA) .ASCII "TEXT" .BYTE ADDRESS .... ETC.... AND WE'LL ENTER WITH .┴┘ CONTAINING THE ADDRESS OF THE TABLE. ╙O BASICALLY WE COME UP WITH THE FOLLOWING: ------------------------------------------------------------------------------- WRITE'TXT = * STA ZP1 ; SAVE .AY IN TABLE ADDRESS STY ZP1+1 LDY #$00 LOOP'W'TEXT = * JSR GET'BYTE ; SET ADDRESS. STA WRK JSR GET'BYTE STA WRK+1 JSR GET'BYTE ; GET # OF CHARS TO WRITE OUT. CMP #$00 BEQ + ; IF ZERO THEN EXIT. TAX JSR SETADRS ; SET ADDRESS TO WRK,WRK+1 - JSR GET'BYTE JSR WRITEBYTE ; WRITE OUT BYTE. DEX BNE - SEC BCS LOOP'W'TEXT ; THIS IS AN ABSOLUTE JUMP TO LOOP + RTS ; RETURN. ------------------------------------------------------------------------------- ╘HIS IS SIMILAIR TO OUR PREVIOUS ROUTINE, AND WAS IN FACT COPIED AND MODIFIED FROM THE PREVIOUS ROUTINE. ╓╔╔╔. ─EBUGGING --------- ╬OW, NOT ALL PROGRAMS ARE PERFECT, AND DURING THE DEVELOPMENT OF THIS PORTION OF THE GAME THERE WERE SEVERAL ERRORS FOUND. ╘RACING AN ERROR IN ═ACHINE/┴SSEMBLY-╠ANGUAGE IS LIKE TRYING TO FIND A GRAMMATICAL ERROR IN A LANGUAGE YOU DON'T KNOW. ;-) ┬UT SERIOUSLY, THERE ARE SEVERAL WAYS TO TRACK DOWN ERRORS IN YOUR CODE. 1 - ╘RY TRACING IT THROUGH BY HAND PLAYING "╫HAT IF ╔ WERE THE COMPUTER" AND FOLLOWING WHAT EACH REGISTER DOES. 2 - ┴RE YOU SWITCHING THE ╠O╚I ORDER OF VARIABLES? ╔E: IS IT LDA #< OR LDA #>?? 3 - ╙ET ┬╥╦ POINTS AND RUN THE PROGRAM / SUBROUTINE WITHIN A MACHINE LANGUAGE MONITOR AND MAKE SURE THE REGISTERS / MEMORY LOCATIONS CONTAIN THE VALUES THAT THEY SHOULD. ╔F NOT, FIND OUT WHY. 4 - ╘RY TO SIMPLIFY YOUR CODE IN TERMS OF PROGRAMMING EASE - ═AKE THE ASSEMBLER DO THE WORK FOR YOU - IT'S A LOT LESS LIKELY TO MAKE ERRORS THAN YOU ARE. 5 - ╘HINK LOGICALLY!!! 6 - ├HANGE SOMETHING AT RANDOM AND PRAY. ╔ CAN'T STRESS NUMBERS 3 AND 5 ENOUGH. ─URING THE WRITING OF THE INSTALL'CHAR ROUTINE THERE WERE NUMEROUS BUGS THAT WERE EVENTUALLY TRACKED DOWN BY SETTING A ┬╥╦ INSTRUCTION FURTHER ALONG IN THE CODE AND SEEING EXACTLY WHAT THE REGISTER / MEMORY LOCATIONS WERE. ┴LSO THE USE OF TEMPORARY LOAD AND STORE INSTRUCTIONS INTO "SAFE" REGIONS OF MEMORY HELPED ME MONITOR WHAT SOME OF THE VALUES WERE. ╞OR EXAMPLE, AT ONE POINT ╔ HAD A SECTION OF CODE SIMILAIR TO THE FOLLOWING: CLC LDA VALUE ADC DATA BNE + INC DATA+1 + [.... ] ┴ND IT'S PURPOSE WAS TO ADD VALUE TO DATA. ╬OW ╔'VE FOUND SIMPLE ERRORS ARE USUALLY FOUND LAST, AFTER COMPLEX ERRORS. ┴ND NOT UNTIL A SET A BREAK POINT LIKE: CLC LDA VALUE ADC DATA <-----═ISSING ╔NSTRUCTION AFTER HERE-------------+ BNE + ▄ INC DATA+1 ▄ + ┬╥╦ ▄ [.... ] ▄ ▄ DID ╔ ACTUALLY FIGURE OUT THAT ╔ WAS MISSING THE ╙╘┴ ─┴╘┴ INSTRUCTION --+ ╙O, WHEN WRITING, MODIFYING, AND TRYING TO DEBUG CODE TRY TO TAKE YOUR TIME AND ISOLATE EVERY POSSIBLE PROBLEM. ┴LSO DON'T BE AFRAID TO STOP THE CODE MID-STREAM AS IN THE ABOVE WITH USE OF THE ┬╥╦. ┘OU CAN ALWAYS REMOVE IT (AND PROBAHLY SHOULD) IN THE FINAL CODE AND IT SERVES AS A VERY VALUABLE DEBUGGING TOOL WITH THE AID OF A MACHINE-LANGUAGE MONITOR. ╔╪. ═EMORY ═AP ├ONSIDERATIONS ------------------------- ┬EFORE YOU START A PROGRAM IT'S A GOOD IDEA TO CONSIDER WHERE IN MEMORY YOU WILL HAVE EVERYTHING. ╬OW WE'VE ALREADY STARTED SOME OF THE PROGRAM ABOVE AND JUST BLINDLY PICKED NUMBERS AT RANDOM IT SEEMED LIKE $3000 FOR THE CHARACTER SET FOR THE ├=64 ETC... ╫E DIDN'T - ╔'M INTRODUCING THE ═EMORY ═AP ├ONSIDERATIONS HERE TO SHOW THE EXAMPLE OF WHAT IF WE DIDN'T THINK ABOUT HOW MEMORY WAS GOING TO BE ORGANIZED. ╘HE ├=64 ONLY HAS 64K OF MEMORY OF WHICH TYPICALLY THE RANGE $0800-$A000 IS AVAILABLE AND $C000-$CFFF IS ALSO. ╔F WE HAD BLINDLY PICKED NUMBERS ALL OVER THE PLACE TO STORE OUR CODE THEN WE WOULD HAVE A DISORGANIZED PROGRAM THAT WOULD MOST LIKELY ACCIDENTALLY USE ONE SUBROUTINES STORAGE AS TEMPORARY DATA FOR ANOTHER. ╔T'S LIKE SHOOTING RANDOMLY IN ╠ASER ╘AG NOT CHECKING TO SEE IF THERE IS A TARGET THERE OR NOT FIRST... ╘HE END RESULT: ├HAOS. ├URRENTLY WE'RE NOT FOLLOWING THE RULE FOR "TEMPORARY VARIABLES" BUT AS WE GRADUALLY FADE OUT OF THE NORMAL ├-64/128 DEFAULT MODE AND WRITE OUR OWN ROUTINES / INTERRUPT HANDLERS WE'LL SWITCH THINGS OVER. ┴LSO, ON THE ├=128 INSTEAD OF USING ┬ANK 0 WITH THE ╔/╧ BLOCK ENABLED WE'RE CURRENTLY USING THE ┬┴╬╦ 15 CONFIGURATION AS THE PROGRAM DOESN'T EXTEND PAST $4000 YET ($0000-$4000 IS COMMON MEMORY IN THE NORMAL ├=128 CONFIGUARTION). 64 ├ONSIDERATIONS ----------------- ╘HE 64 WILL HAVE FREE MEMORY IN THE FOLLOWING AREAS: $0800-$A000, AND $C000-$CFFF. ╚OWEVER, IF WE DISABLE THE ┬ASIC ╥OM WE CAN HAVE THE WHOLE AREA FROM $0800-$CFFF FREE FOR OUR PROGRAM. ┬ECAUSE WE DON'T NEED THE ┬ASIC ╥OM WE WILL DO JUST THAT (IN THE LISTING NOW WE CURRENTLY WON'T BUT IT WILL BE DONE IN A FUTURE ISSUE). ╘HEREFORE HAVING THE CHARACTER SET AT $3000-$5000, THE MUSIC DATA AT $5000-$8000, THE PROGRAM WILL HAVE THE AREA FREE FROM $8000-$CFFF. $0800-$3000 WILL BE AVAILABLE IF NEEDED FOR ROUTINES WHO NEED TEMPORARY STORAGE. ╘EMPORARY ╙TORAGE IS GOING TO BE DEFINED AS FOLLOWS. ┼ACH ROUTINE THAT NEEDS TEMPORARY STORAGE WILL BE ASSIGNED A "LEVEL" NUMBER. ╘HE LOWER LEVELS WILL BE ASSIGNED LEVEL 1 ON UP TO LEVEL 3. ╘HE RANGE $0800-$3000 WILL BE BROKEN DOWN INTO THE FOLLOWING SUB-RANGES. ╠EVEL 1: $0800-$1000 ╠EVEL 2: $1000-$1800 ╠EVEL 3: $1800-$3000 ╘HIS WAY WHEN WRITING THE SUB-ROUTINES WE CAN BE ASSURED THAT A SECTION OF MEMORY IS NOT OVERWRITTEN BY A SUBROUTINE WE CALL. ╫HEN WE ACTUALLY START PROGRAMMING WE'LL DECIDE WHERE IN EACH SUB-RANGE THE ROUTINE WILL HAVE ACCESS TO. 128 ├ONSIDERATIONS ------------------ ╘HE 128 HAS TWO "BANKS" OF 64K EACH. ╬ORMALLY FOR LARGE PROGRAMS WE WOULD THINK ABOUT USING BOTH BANKS - (FROM THE IDEA: ╚EY! - ╫E GOT IT, WHY NOT FLAUNT IT?) BUT WE WON'T BE USING BOTH BANKS. ╞REE MEMORY ON THE ├128 TYPICALLY CONSISTS OF THE RANGE $0400-$09FF (WHERE WE'LL BE OVERWRITING THE 40 COLUMN SCREEN (WHICH WE'RE GONNA BLANK ANYWAY) AND THE ┬ASIC RUN-TIME STACK.) ┴LSO THE AREA FROM $0B00-$0FFF IS FREE (OVERWRITING THE TAPE AREA, THE RS-232 BUFFERS,L AND THE SPRITE DEFINITION AREA). ┴LSO $1300-$CFFF WILL BE FREE. ╬OW, THE ├=128 HAS DIFFERENT MEMORY MAPS IT CAN CONFIGURE ITSELF TO - ┬ANK 15 IS THE STANDARD MODE UNDER MOST BASIC PROGRAMS AND ALLOWS THE PROGRAMMER TO DIRECTLY "SYS" TO CALLS. ╘HE ══╒ (MEMORY MANAGEMENT UNIT - THE CHIP THAT DOES EVERYTHING) SEES MEMORY IN A SLIGHTLY DIFFERANT WAY THAN FROM BASIC. ╫E'LL COVER IT IN MORE DETAIL WHEN WE EXAMINE THE MEM_INIT ROUTINE. ╞OR NOW, WE'RE JUST GONNA SET UP IN THE PROGRAM AND NOT IN THE CODING SEGMENTS. ╘HE EXPLANATION OF WHAT WE'RE DOING WILL BE "REVEALED" IN A FUTURE ISSUE. ╫E WILL USE ┬ANK 0 OF MEMORY AND FROM $1300+ WILL BE THE PROGRAM. ╘HE RANGES OF $0400-$09FF AND $0B00-$0FFF WILL BE USED IN A SIMILAIR MANNAR AS THE ├64 RANGES WERE FOR ╘EMPORARY ╙TORAGE. ╫E WILL ALSO HAVE THE ╔/╧ SECTION FROM $D000-$DFFF SWAPPED IN. ╘HIS IS NOT A STANDARD "BASIC ┬┴╬╦ #" BUT WHEN WE COVER THE INIT'MEMORY ROUTINE WE'LL SEE HOW WE CAN DO THIS. ═USIC DATA WILL BE FROM $A000-$D000. ╪. ╠OOKING ╞ORWARD / ┬ACK ---------------------- ╚OPEFULLY THROUGH THE LISTING AND THE DISCUSSION OF THE ROUTINES YOU HAVE STARTED TO UNDERSTAND THE BASIC CONCEPT OF PROGRAMMING: BREAKING DOWN PROBLEMS INTO SMALLER SOLVABLE STEPS. ╘RY LOOKING BACK OVER THE CODE ASKING YOURSELF WHY THAT INSTRUCTION IS THERE. ╫HAT WOULD HAPPEN IF YOU SWITCHED THE ORDER? ╔S THERE AN EASIER, BETTER WAY TO DO THE SAME THING? ╫HY? ┬ETTER YET, HOW? ┼XAMINE THE CODE, MESS WITH IT, MUCK IT UP SO IT DOESN'T WORK AND THEN FIGURE OUT EXACTLY WHY. ╘HE ONLY WAY TO LEARN IS BY EXPERIMENTATION. (┬╘╫, MUCK UP A _COPY_ OF IT - NOT THE ORIGINAL ... *GRINS*) ╘AKE A LOOK AT THE DIFFERENT SECTIONS OF CODE AND ANALYZE THEM TO SEE HOW THEY DO WHAT THEY DO. ╘AKE A LOOK AT HOW THE CODE WAS ORGANIZED IN TERMS OF SIMPLIFICATION. ╘RACE THROUGH EACH SUBROUTINE SO THAT YOU'RE ABLE TO KNOW WHAT THE RETURN VALUES WILL BE. ╔N OTHER WORDS: ╙TUDY, ╙TUDY, ╙TUDY!! ╔'M IN SCHOOL AND SO ╔ KNOW ╔ JUST USED THE DREADED '╙' WORD BUT THAT'S WHAT YOU'RE GOING TO HAVE TO DO IF YOU'RE INTERESTED IN LEARNING 65XX/85XX MACHINE LANGUAGE. ╘HE ONLY WAY TO LEARN IT (EASILY) IS TO STUDY OTHER PEOPLE'S CODE AND TRY TO UNDERSTAND WHY THEY DID WHAT THEY DID. ╬EXT TIME WE WILL TAKE A LOOK AT THE INPUT ROUTINES FOR THE MOUSE, JOYSTICK AND KEYBOARD SCANNING. ╔N ADDITION WE WILL ALSO ALLOW THE PLAYER TO MOVE THE SHIP AROUND ON THE SCREEN TO TEST THE INPUT DRIVERS. ╔N ADDATION, ╔ AM STILL LOOKING FOR AN INDIVIDUAL TO HELP WITH MUSIC AND SOUND COMPOSITION FOR THIS PROGRAM. ┴ KNOWLEDGE OF THE ╙╔─ CHIP AND PROGRAMMING IS HELPFUL BUT NOT REQUIRED. ╔F YOU'RE WILLING TO HELP THEN PLEASE EMAIL ME AT DUCK@PEMBVAX1.PEMBROKE.EDU ╪╔. ╠ISTINGS -------- ┬ECAUSE OF THE ENORMITY OF THE PROGRAM LISTING (SOME 1,500+ LINES) IT WILL NOT BE LISTED IN THIS ARTICLE BUT WILL INSTEAD BE AVAILABLE VIA ANONYMOUS FTP AT CCOSUN.CALTECH.EDU UNDER PUB/RKNOP/╚┴├╦╔╬╟.═┴╟ AS INVAS1.SFX. ╞OR THOSE OF YOU ON THE MAILING LIST WHO WOULD LIKE TO RECIEVE IT, A ═AIL- ╙ERVER WILL BE SET UP SOON TO HANDLE REQUESTS AND INFORMATION WILL BE SENT TO YOU CONCERNING INFORMATION ABOUT USING IT AS SOON AS IT'S COMPLETED. ╔N THE INVASION1.SFX FILE THERE ARE THE FOLLOWING FILES: INVASION.SRC - THE MAIN FILE GRAPHICS.SRC - HANDLES ALL GRAPHICS ROUTINES LOGO.DAT - CUSTOM CHARACTER LOGO CHARS64.DAT - ALIEN CUSTOM CHARACTERS FOR ├=64 CHARS128.DAT - ALIEN CUSTOM CHARACTERS FOR ├=128 TITLETXT.DAT - TEXT DATA FOR TITLE SCREEN TITLECOL.DAT - COLOR DATA FOR TITLE SCREEN INVASION-128 - EXECUTABLE VERSION OF ╙PACE ╔NVASION SO FAR FOR ├=128 INVASION-64 - EXECUTABLE VERSION OF ╙PACE ╔NVASION SO FAR FOR ├=64 ╬OTE: ╞OR THE ├OMMODORE 128 IT'S RECOMMENDED THAT YOU DO A RUN/STOP-RESTORE AND THEN A "┬┴╬╦15:╙┘╙7168" TO EXECUTE THE PROGRAM. ╞OR THE ├OMMODORE 64 IT'S RECOMMENDED THE BORDER BE CHANGED VIA: "╨╧╦┼53280,0:╨╧╦┼53281,0:╙┘╙ 32768" TO RUN THE PROGRAM. ============================================================================== ╘HE ─EMO ├ORNER: ╞╠╔ - MORE COLOR TO THE SCREEN BY ╨ASI '┴LBERT' ╧JALA (PO87553@CS.TUT.FI OR ALBERT@CC.TUT.FI) ╫RITTEN ON 16-═AY-91 ╘RANSLATION 01-╩UN-92 (┴LL TIMINGS ARE IN ╨┴╠, ALTHO THE PRINCIPLES WILL APPLY TO ╬╘╙├ TOO) ┴LL OF US HAVE HEARD COMPLAINTS ABOUT THE COLOR CONSTRAINTS ON ├64. ╧NE 8X8 PIXEL CHARACTER POSITION MAY ONLY CARRY FOUR DIFFERENT COLORS. ╞╠╔ PICTURE CAN HAVE ALL OF THE 16 COLORS IN ONE CHAR POSITION. ╫HAT THEN IS THIS ╞╠╔ AND HOW IT IS DONE ? ╔N THE NORMAL MULTICOLOR MODE CAN ONE CHARACTER POSITION (4X8 PIXELS) HAVE ONLY FOUR DIFFERENT COLORS AND ONE OF THEM IS THE COMMON BACKGROUND COLOR. ├OLOR CODES ARE STORED IN HALF BYTES (NYBBLES) TO THE VIDEO MATRIX MEMORY (ANYWHERE VIDEO MATRIX POINTER POINTS AT, NORMALLY $0400) AND TO THE COLOR MEMORY ($─800-$─┬╞╞). ╔N MULTICOLOR MODE THE COLOR OF EACH PIXEL IS DETERMINED BY TWO BITS IN THE GRAPHICS MEMORY. ┬IT PAIR 11 WILL REFER TO COLOR MEMORY, BACKGROUND COLOR IS THE COLOR FOR BIT PAIR 00, AND VIDEO MATRIX WILL DEFINE THE COLORS FOR BIT PAIRS 01 AND 10. _╫HAT HAPPENS IN THE ╓╔├ ?_ ╓╔├ (╓IDEO ╔NTERFACE ├ONTROLLER) FETCHES COLOR INFORMATION FROM MEMORY ON EACH BAD LINE. ╘HIS WILL STEAL TIME FROM PROCESSOR, BECAUSE ╓╔├ NEEDS TO USE PROCESSOR'S BUS CYCLES. ┬AD LINE IS A CURSE IN THE ├64 WORLD. ╞ORTUNATELY ╓╔├'S DATA BUS IS 12 BITS WIDE AND SO THE COLOR DATA FETCH FOR EACH CHARACTER POSITION WILL TAKE ONLY ONE BUS CYCLE. ├OLOR MEMORY IS PHYSICALLY WIRED TO THE ╓╔├ DATABUS LINES ─8-─11. ╚OW DOES ╓╔├ KNOW WHERE TO FETCH THE GRAPHICAL INFORMATION ? ╙OME OF YOU KNOW THE MYSTICAL FORMULAS NEEDED TO MESS WITH THE PIXELS IN THE HIRES SCREEN. ╚OW ARE THESE FUNCTIONS OBTAINED ? ┴RE THEY JUST MAGIC ? ╬O, THERE ARE SOME INTERNAL COUNTERS IN ╓╔├. ╘HEY ALWAYS POINT TO THE RIGHT PLACE IN GRAFIX MEMORY AND THE ADDRESS IS DETERMINED LIKE THIS: ┴13 ┴12 ┴11 ┴10 ┴9 ┴8 ┴7 ┴6 ┴5 ┴4 ┴3 ┴2 ┴1 ┴0 ├┬13 ╓├9 ╓├8 ╓├7 ╓├6 ╓├5 ╓├4 ╓├3 ╓├2 ╓├1 ╓├0 ╥├2 ╥├1 ╥├0 ┴DDRESS BITS ┴15 AND ┴14 CHANGE ACCORDING TO THE SELECTED VIDEO BANK. ┴DDRESS BIT ┴13 IS ├┬13, WHICH MAY BE FOUND IN ╓╔├ REGISTER $18. ╔T SELECTS THE RIGHT SIDE OF THE VIDEO BANK TO BE THE BITMAP MEMORY. ╫ITH THESE BITS YOU CAN SET THE BITMAP TO EIGHT DIFFERENT PLACES IN MEMORY. ╚OWEVER, SOME OF THEM ARE USELESS BECAUSE OF THE CHARACTER ╥╧═ IMAGES AND ZERO PAGE/STACK. ╥EST OF THE BITS COME FROM THE INTERNAL COUNTERS. ╓├9-╓├0 (╓IDEO ├OUNTER) FORMS THE ADDRESS BITS 12-3. ╘HE COUNTER ROLLS THROUGH ALL 1000 CHARACTER POSITIONS, 0-39 ON THE FIRST EIGHT LINES, 40-79 ON THE SECOND EIGHT LINES AND SO ON. ╘HE LOWEST THREE BITS COME FROM THE ROW COUNTER, ╥├2-╥├0. ╘HIS IS ANOTHER ╓╔├ COUNTER AND IT COUNTS THE SCAN LINES FROM ZERO TO SEVEN. _┴ SOFTWARE GRAPHICS MODE - ╞╠╔_ ╓╔├ WILL SYSTEMATICALLY GO THROUGH EVERY BYTE IN THE BITMAP MEMORY, BUT HOW DOES IT KNOW WHERE AND WHEN TO GET THE COLOR INFORMATION ? ╘HIS IS WHERE THE MAIN PRINCIPLE OF ╞╠╔ (╞LEXIBLE ╠INE ╔NTERPRETATION) LIES. ├OLOR DATA IS FETCHED (AND THIS MEANS IT IS A BAD LINE), WHEN THE LINE COUNTER MATCHES WITH THE VERTICAL SCROLL REGISTER. ╓├9-╓├0 DEFINES WHERE THE COLOR DATA IS INSIDE THE VIDEO MATRIX AND COLOR MEMORY. ╔F WE CHANGE THE VERTICAL SCROLL REGISTER, WE CAN FOOL ╓╔├ TO THINK THAT EVERY LINE IS A BAD LINE, SO IT WILL FETCH THE COLOR INFORMATION ON EVERY LINE TOO. ┬ECAUSE ╓╔├ WILL FETCH THE COLORS CONTINUOSLY, WE CAN GET INDEPENDENT COLORS ON EACH SCAN LINE. ╫E JUST HAVE TO CHANGE COLORS AND ╓╔├ WILL HANDLE THE REST. ╒NFORTUNATELY THE RESULT IS THE LOSS OF 40 PROCESSOR CYCLES PER LINE (SEE THE ═ISSING ├YCLES ARTICLE FOR MORE INFORMATION ABOUT ╓╔├ STEALING CYCLES). _─OING IT IN PRACTICE_ ╔N PRACTICE THERE IS NO TIME TO CHANGE COLOR MEMORY, BUT IN MULTICOLOR MODE ╓╔├ USES VIDEO MATRIX FOR COLOR INFORMATION TOO. ╫E HAVE JUST ENOUGH TIME TO CHANGE THE VIDEO MATRIX POINTER, $─018. ╬OW ╓╔├ WILL SEE A DIFFERENT VIDEO MATRIX ON EACH SCAN LINE, DIFFERENT BLOCK OF MEMORY. ╫ITH THE FOUR UPPER BITS IN THE REGISTER WE SELECT ONE OF THE 16 VIDEO MEMORIES IN THE VIDEO BANK. ╩UST REMEMBER THAT THE REGISTER ALSO SELECTS THE POSITION OF THE GRAPHICS MEMORY (BITMAP) INSIDE THE VIDEO BANK. ┬ECAUSE WE HAVE TO KEEP THE BITMAP IN THE SAME VIDEO BANK, WE ONLY HAVE HALF OF THE BANK FREE FOR VIDEO MATRICES. ╞ORTUNATELY, THAT'S ALL WE NEED TO GET INDIVIDUAL MULTICOLOR COLORS FOR EACH LINE AND CHARACTER POSITION. ╓╔├ WILL FETCH THE COLOR DATA FROM THE EIGHT VIDEO MATRICES AND THEN IT WILL ROLL ON TO THE NEXT 40 BYTES. ┴FTER EIGHT LINES AND MATRICES WE WILL SELECT THE FIRST VIDEO MATRIX AGAIN. (╙EE PICTURE 1) ╒SUALLY IT IS NOT NECASSARY TO USE THE WHOLE SCREEN FOR A ╞╠╔ PICTURE, ESPECIALLY IF YOU WANT TO HAVE A SCROLLER OR SOME OTHER EFFECTS. ┘OU JUST HAVE TO MAKE SURE THAT ╓╔├ IS FOOLABLE IN THE USUAL WAY. ╘HE TIMING IS ALSO VERY IMPORTANT, EVEN ONE CYCLE VARIATIONS IN THE ROUTINE ENTRY ARE NOT ALLOWED. ╘HERE IS MANY WAYS TO DO THE SYNCHRONIZATION. ╧NE WAY IS TO USE A SPRITE, AS IN THE PREVIOUS ARTICLE. (╙EE ├= ╚ACKING, ╓OL. 1, ╔SS. 3, ╘HE ─EMO ├ORNER: ═ISSING ├YCLES). _╬OT MUCH TIME_ ┬ECAUSE A BAD LINE WILL STEAL 40 CYCLES, THERE IS ONLY 23 CYCLES LEFT ON EACH SCAN LINE. ╔T IS ENOUGH FOR CHANGING THE VIDEO MATRIX AND BACKGROUD COLOR. ╘HERE IS NOT A MOMENT TO LOSE, BECAUSE YOU MUST CHANGE THE VERTICAL SCROLL REGISTER, VIDEO MATRIX POINTER AND THE BACKGROUND COLOR. ╘HIS IS WHY YOU CAN'T HAVE SPRITES IN FRONT OF A ╞╠╔ PICTURE. ╫ITH ╞╠╔ WE GET TWO SELECTABLE COLORS FOR EACH CHARACTER POSITION AND LINE, EACH SCAN LINE CAN HAVE IT'S OWN BACKGROUND COLOR AND EACH CHARACTER POSITION STILL HAS ITS OWN CHARACTER COLOR FROM COLOR MEMORY. ╔N THEORY EACH CHARACTER POSITION COULD HAVE 25 DIFFERENT COLORS, UNFORTUNATELY ╓╔├ ONLY HAS 16. _┴ LITTLE FEATURE_ ╓╔├ DOES NOT LIKE IT WHEN WE CHANGE THE VERTICAL SCROLL REGISTER ($─011), AND IS A BIT ANNOYED. ╔T 'SEES' CODE 255 (LIGHT GRAY) IN VIDEO MATRIX AND 9 (BROWN) IN THE COLOR MEMORY INSTEAD OF THE CORRECT VALUES STORED THERE. ┴CTUALLY THE COLOR VALUE SEEMS TO BE THE LOWER NYBBLE OF THE DATA BYTE CURRENTLY ON THE DATA BUS (ACCESSED BY THE PROCESSOR (╠─┴#=$┴9)). ╒NFORTUNATELY THERE IS NO CHANCE TO DO THE REGISTER CHANGE IN THE BORDER AND THUS THE THREE LEFTMOST CHARACTER COLUMNS ARE A BIT USELESS, BECAUSE THE COLORS ARE FIXED. ╚OWEVER, THIS DOESN'T MEAN THAT YOU CAN'T USE THOSE THREE COLUMNS. ╞╠╔ EDITORS MAY NOT SUPPORT THE FIXED COLORS THOUGH, SO IT MAY BE HARD TO USE THEM. _╫HAT TO DO WITH ╞╠╔ ?_ ┬ECAUSE ╞╠╔ WILL EAT UP ALL THE AVAILABLE PROCESSOR TIME (NO ├OPPER :-), IT IS NOT SUITABLE FOR ANY ACTION-GAMES. ┼ACH ╞╠╔ PICTURE TAKES ABOUT 17 K┬ OF MEMORY: NOT SO MANY PICTURES FIT ON ONE FLOPPY. ╙O, THE ONLY PLACE FOR ╞╠╔ IS DEMOS, INTROS, BOARD-TYPE GAMES AND MAYBE A ╟╔╞ VIEWER.. -------------------------------------------------------------------------- ╨ICTURE 1: ╞ROM WHICH MATRIX ╓╔├ FETCHES THE MULTICOLOR VALUES _ ___________________________________________________________ ▄ ... ▄ ═ATRIX0 ▄ ═ATRIX0 ▄ ═ATRIX0 ▄ ▄ , .▄____3__________▄____4__________▄____5__________▄ ... ▄ ╒ .▄ ═ATRIX1 ▄ ═ATRIX1 ▄ ═ATRIX1 ▄ ▄ S .▄____3__________▄____4__________▄____5__________▄ . ▄├HAR E ▄ ═ATRIX2 ▄ ═ATRIX2 ▄ ═ATRIX2 ▄ . ▄╠INE L ▄____3__________▄____4__________▄____5__________▄ . ▄┌ERO E ▄ ═ATRIX3 ▄ ═ATRIX3 ▄ ═ATRIX3 ▄ ▄ S ▄____3__________▄____4__________▄____5__________▄ ▄ S, ▄ ═ATRIX4 ▄ ═ATRIX4 ▄ ═ATRIX4 ▄ ▄ ▄____3__________▄____4__________▄____5__________▄ ▄ C ▄ ═ATRIX5 ▄ ═ATRIX5 ▄ ═ATRIX5 ▄ ▄ O ▄____3__________▄____4__________▄____5__________▄ ▄ L ▄ ═ATRIX6 ▄ ═ATRIX6 ▄ ═ATRIX6 ▄ ▄ U ▄____3__________▄____4__________▄____5__________▄ ▄ M ▄ ═ATRIX7 ▄ ═ATRIX7 ▄ ═ATRIX7 ▄ ▄_ N ▄____3__________▄____4__________▄____5__________▄ S ▄ ═ATRIX0 ▄ ═ATRIX0 ▄ ═ATRIX0 ▄ ▄___43__________▄___44__________▄___45__________▄ ▄ ═ATRIX1 ▄ ═ATRIX1 ▄ ═ATRIX1 ▄ ▄___43__________▄___44__________▄___45__________▄ ▄ ▄ ... ▄ . ▄ . ▄ . -------------------------------------------------------------------------- _┴DDITIONAL READING_ ╔F YOU HAVE AN ┴MIGA YOU MIGHT WANT TO GET YOUR HANDS INTO MY CONVERSION PROGRAMS IN ├64╟╞╪1.LHA. ╘HE PACKET ALSO INCLUDES ╞╠╔ VIEWER FOR ╨┴╠ ├64'S AND SOME DOCUMENTATION ABOUT THE ╞╠╔ FILE FORMAT. ╔T ALSO HAS THE SAME UTILITIES FOR ╦OALA FORMAT PICTURES. ┴VAILABLE FROM: CWAVES.STFX.CA NIC.FUNET.FI:/PUB/AMIGA/GRAPHICS/APPLICATIONS/CONVERT ├64╟╞╪.DOC ├64╟FX1.0 ┴ ├64 GRAFIX FORMAT CONVERSION PACKAGE )1991,1992 ╨ASI '┴LBERT' ╧JALA ┼-MAIL: PO87553@CS.TUT.FI ALBERT@CC.TUT.FI ╘HIS PACKAGE CONTAINS PROGRAMS WHICH ARE USED TO CONVERT PORTABLE PIXMAP (PPM) FILES TO ├64 GRAPHICS FORMATS (╞╠╔ AND KOALA) UNDER ┴MIGA╧╙. ╘HE PACKAGE INCLUDES ├ SOURCE CODES FOR THE PROGRAMS, SO IT IS POSSIBLE TO PORT THE PROGRAMS TO ANOTHER ENVIRONMENT. ├64╟╞╪1.1 INCLUDES ╒NIX-COMPILABLE SOURCES. ╔N ADDITION TO THIS PACKAGE YOU NEED E.G. ╨┬═╨LUS TO CONVERT ┴MIGA ILBM FILES TO PPM FIRST. ┴ND OF COURSE SOME WAY TO TRANSFER FILES BETWEEN THE MACHINES. ============================================================================= ╥╙-232 ├ONVERTER BY ╫ARREN ╘USTIN (WARREN@COL.HP.COM) ╘HIS ARTICLE PRESENTS A WAY TO INTERFACE FROM THE ├= RS232 HARDWARE BEHIND THE USER PORT TO A STANDARD 25PIN FEMALE RS232 CONNECTOR USING ONLY ONE ╔├ AND A FEW CAPACITORS. ╔T IS NOT A ╒┴╥╘ OR A ╙╫╔╞╘╠╔╬╦ TYPE INTERFACE WHICH TAKE PLACE OF THE INTERNAL ├= RS232 CIRCUITRY, BUT A SIMPLE LEVEL SHIFTING INTERFACE THAT USES THE INTERNAL RS232 ROUTINES AND TRANSLATES THE USER PORT LEVELS TO RS232 LEVELS. ╘HEREFORE YOU CAN ONLY GET UPTO 2400BAUD/9600BAUD (├=64/├=128) WITH THIS DESIGN. ╘HE "OLD" WAY TO DO THIS WAS TO USED ═├1488 AND ═├1489 PARTS (A LINE DRIVER AND LINE RECEIVER), HOWEVER THESE REQUIRED A NEGATIVE SUPPLY TO INTERFACE PROPERLY. ╘HE USER PORT ONLY SUPPLIES +5VOLTS, HENCE THIS PRESENTS A PROBLEM. ╘HERE HAS BEEN SUCCESS USING THESE PARTS OR DISCRETE TRANSISTORS AND RESISTORS SINCE MANY MODEMS ARE SOMEWHAT FRIENDLY AND SEEM TO WORK EVEN THOUGH THE LEVELS WERE MARGINAL. ┴LSO, SOME SIGNALS WERE NOT USED, ALLOWING FOR POTENTIAL PROBLEMS. ┴NOTHER WAY TO SOLVE THIS PROBLEM WAS TO BUY A $25-30 INTERFACE. ╔F YOU CAN FIND THE ╔├ BELOW, YOU HAVE ANOTHER CHOICE THAT IS RELATIVELY INEXPENSIVE. ╘HE ╠╘1133 IS BASICALLY THE ═├1488 AND 1489 PUT TOGETHER INTO ONE PART WITH AN INTERNAL CHARGE PUMP SCHEME THAT ALLOWS THE INTERNAL DRIVERS TO OUTPUT +5 AND -5 VOLTS TO THE RS232 CONNECTOR. ╔T ALSO HAS ENOUGH DRIVERS AND RECEIVERS TO HANDLE ALL OF THE SIGNALS THAT THE ├= USES FOR RS232. ╙O WITH THIS ╔├, 5 CAPACITORS AND THE TWO CONNECTORS (USER PORT AND RS232) YOU CAN BUILD YOUR OWN INTERFACE TO THE STANDARD 25 PIN MODEM CABLE. ╚ERE ARE THE PLANS FOR AN ╒SER PORT ╘╧ ╥╙232 CONNECTOR USING JUST ╧╬┼ ╔├ AND 4 CAPACITORS. ╔T USES A ╠INEAR ╘ECHNOLOGY ╠╘1133 BUFFER THAT HAS 3 ╥╙232 DRIVERS AND 5 RECEIVERS. ╔T HAS WORKED FOR ME WITH NO PROBLEMS AND TAKES A MINIMUM AMOUT OF WIRING TO GET TO WORK. ═Y BOARD IS ONLY THE WIDTH OF THE USER PORT AND ABOUT 1.5 INCHES DEEP IN SIZE. ╨ARTS LIST: ---------- ╠╘1133├╬ PLASTIC DIP OR ╠╘1133├╩ CERAMIC DIP ╥╙232 DRIVER FROM ╠INEAR ╘ECHNOLOGIES (╔T TAKES 27M┴ MAX (17M┴ TYPICAL) SO IS WELL BELOW THE 100M┴ LIMIT OF THE USER PORT) ─RIVER ╔N PINS (15,19,21) ╘╘╠/├═╧╙ COMPATIBLE. ╒NUSED INPUTS ▄ ▄ ▄ SHOULD BE TIED TO +5V. ─RIVER ╧UT PINS (11, 7, 5) ╥╙232 COMPATIBLE. ╙HORT CIRCUIT PROTECTED FROM -30V TO +30V. ╥ECEIVER ╔N PINS (6, 8, 9, 10,12) ┴CCEPT ╥╙232 LEVELS (+-30V) ▄ ▄ ▄ ▄ ▄ AND HAVE 0.4V OF HYSTERESIS TO ▄ ▄ ▄ ▄ ▄ PROVIDE NOISE IMMUNITY. ╥ECEIVER ╧UT PINS (20,18,17,16,14) ╘╘╠/├═╧╙ OUTPUTS. ╬╧╘┼: ╠INES ABOVE INDICATE WHICH INPUTS GO WITH WHICH OUTPUTS, AND THE PAIRS CAN BE INTERCHANGED FREELY. ╔ CONNECTED THEM AS DESCRIBED BELOW BECAUSE THE WIRING WORKED OUT THE BEST FOR ME. 4 - >= 1U╞ CAPACITORS ╒SED TO GENERATE ╥╙232 VOLTAGES BY A CHARGE PUMP TECHNIQUE INSIDE ╔├ 1 1U╞ CAPACITOR ╘O BYPASS THE 5VOLT SUPPLY FOR NOISE REJECTION. 1 ╒SER PORT FEMALE CONNECTOR. (╔ JUST DUG THIS UP, ╔'M NOT SURE WHERE THESE CAN BE FOUND, ╔ THINK IT IS 0.159" SPACING, 24PIN. 1 ╥╙232 25PIN FEMALE CONNECTOR. ├AN BE FOUND AT ╥-╙HACK ╙OME SORT OF .1" SPACING PROTO BOARD ├ONNECTIONS: ----------- ╒SER PORT CONNECTOR (╠OOKING INTO THE ├64 OR ├128) 1 2 3 4 5 6 7 8 9 10 11 12 ------------------------------------ ▄╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪╪▄ ------------------------------------ ┴ ┬ ├ ─ ┼ ╞ ╚ ╩ ╦ ╠ ═ ╬ ╟ROUND & ╨OWER: -------------- ╨INS 1, ┴, 12, ╬ TO ╟ROUND OF BOARD. ╠╘1133 PIN 2 TO PIN 2 OF ╒SER PORT CONNECTOR (+5 VOLTS) 1U╞ CAPACITOR BETWEEN PIN2 AND GROUND (BYPASS CAP) ╠╘1133 PIN 13 TO ╟ROUND. ╥╙232 CONNECTOR PINS 7 & 1 TO ╟ROUND. ╠╘1133 CAPACITORS: 1U╞ FROM PIN 1 (╓+) TO GROUND (╔F POLARIZED (ELECTROLYTIC) + SIDE TO PIN 1) 1U╞ FROM PIN 24 (╓-) TO GROUND (┴S ABOVE BUT + SIDE TO GROUND) 1U╞ FROM PIN 3 (├1+) TO PIN 4 (├1-) (┴GAIN IF POLARIZED, + SIDE TO PIN 3) 1U╞ FROM PIN 22 (├2+) TO PIN 23 (├2-) (┴GAIN IF POLARIZED, + SIDE TO PIN 22) ├OMMODORE SIDE ╥╙232 SIDE ╒SER PORT ╙IGNAL ╨IN OF ╙IGNAL ╨IN OF ╥╙232 PIN NAME ╠╘1133 DIRECTION ╠╘1133 CONNECTOR --------- ------ ------ --------- ------ --------- ┬ ╞╠┴╟2 ─IN 20 <-- 6 3 ├ ╨┬0 ─IN ALSO CONNECT TO ABOVE PIN 20 ─ ╨┬1 ╥╘╙ 21 --> 5 4 ┼ ╨┬2 ─╘╥ 19 <-- 7 20 ╞ ╨┬3 ╥╔ 18 --> 8 22 ╚ ╨┬4 ─├─ 17 --> 9 8 ╩ ╨┬5 ╬OT USED ╦ ╨┬6 ├╘╙ 16 --> 10 5 ╠ ╨┬7 ─╙╥ 14 <-- 12 6 ═ ╨┴2 ─OUT 15 --> 11 2 ╘HIS ASSUMES THAT YOU WANT TO CONNECT ALL OF THE COMMUNICATION LINES. ╔ DID IT THIS WAY BECAUSE THE ├128 PROGRAMMERS REFERENCE GUIDE HAD ALL OF THE SIGNALS ABOVE LISTED. ╔F YOU WANT TO DROP ╥╔ (RING INDICATOR) YOU COULD ALSO USE AN ╠╘1134 WHICH HAS 4 DRIVERS AND 4 RECEIVERS. ╨ARTS ╙UBSTITUTION: ╘HERE ARE OTHER ╔├'S AVAILABLE WHICH WILL WORK IN THIS APPLICATION. ╘HE RS232 BUS LEVELS FOR THE ╠╘ PARTS ARE SPEC'ED AT ▐ +/- 7V TYPICAL, WHILE THE ═┴╪╔═ PARTS ARE +/-9V TYPICAL. (┬OTH ARE MIN AT +/- 5V WHICH SHOULD WORK IN ALL APPLICATIONS). ╔ THINK THAT AN INTERFACE CAN BE DONE WITH ONLY 3 LINES, ─IN(╥X), ─OUT(╘X), AND EITHER ─╙╥ OR ├╘╙, SO IF YOU CAN'T GET THE ╠╘1133 ONE OF THESE OTHERS MIGHT WORK, ALTHOUGH THE PINOUTS WOULD BE DIFFERENT. ╘HE MAX YOU WOULD NEED IS WHAT THE ╠╘1133 SUPPLIES, 3 DRIVERS & 5 RECEIVERS. ╚ERE IS A DESCRIPTION OF PARTS THAT MIGHT BE SUBSTITUTED: (╬OTE, WITH ALL OF THEM YOU SHOULD USE A BYPASS CAP ON THE +5V SUPPLY WHICH ╔ HAVE ╬╧╘ INCLUDED IN THE COUNTS BELOW.) ╥╙232 ╥╙232 # OF ┼╪╘┼╥╬┴╠ ╬┴═┼ ╨╔╬╙ ─╥╔╓┼╥╙ ╥┼├┼╔╓┼╥╙ ├┴╨╙ ├╧══┼╬╘╙ ------------------------------------------------------------------------- ╠INEAR ╘ECHNOLOGY PARTS... (╧N THE PARTS WITH SHUTDOWN (╙─), THE PIN MUST BE TIED TO +5 TO OPERATE) ╠╘1133 24 3 5 4 ╔N ARTICLE ABOVE ------------------------------------------------------------------------- ╠╘1130 28 5 5 4 ╧VERKILL (╙─P14) ╠╘1131 28 5 4 4 2 EX ─R, 1 < ╥CVR ╠╘1132 24 5 3 4 2 EX ─R, 2 < ╥CVR ╠╘1134 24 4 4 4 1 < ╥CVR ╠╘1136 28 4 5 4 1 EX ─R (╙─P14) ╠╘1137 28 3 5 4 ╙─P13 ╠╘1138 28 5 3 4 ╠╘1132 W/╙─P13 ═┴╪╔═ PARTS... (╙OME ALSO HAVE A ╘╘╠ ┼╬_ PIN THAT MUST BE TIED TO 0V TO OPERATE) (╧N THESE PARTS, ╙─ MUST BE TIED TO 0V TO OPERATE!) ═┴╪232 16 2 2 4 ═AY WORK ═┴╪233 20 2 2 0! ╬O EXTERNAL CAPS ═┴╪235 24 5 5 0! ╧VERKILL, BUT ╬╧ CAPS, ╙─P21, ┼╬_P20 ═┴╪236 24 4 3 4 1 EX ─R, 2 < ╥CVR, ╙─P21, ┼╬_P20 ═┴╪237 24 5 3 4 2 EX ─╥, 2 < ╥CVR ═┴╪238 24 4 4 4 1 EX ─╥, 1 < ╥CVR ╔N SUMMARY, YOU CAN SEE THERE ARE MANY DIFFERENT PARTS YOU COULD USE, ESPECIALLY IF YOU DON'T NEED ALL THE SIGNALS. ╘HE ═┴╪╔═ PARTS SEEM TO DO THE JOB IN FEWER PINS AND A LITTLE BETTER TYPICAL DRIVE SPEC AND ╔ WOULD RECOMMEND THE ═┴╪235 OVERALL SINCE YOU ONLY NEED 1 BYPASS CAP TO MAKE IT OPERATE! ============================================================================= ╔NTRODUCTION TO THE ╓╔├-╔╔ BY ╨ASI '┴LBERT' ╧JALA ( ... ) ╘HE ╓IDEO ╔NTERFACE ├ONTROLLER USED IN ├64 HAVE SEVERAL DIFFERENT OPERATING MODES AND DIFFERENT GRAPHICAL PRIMITIVES. ┬ASICALLY THERE IS A) CHARACTER MODE, B) BITMAP MODE AND C) MOVABLE OBJECTS THAT CAN BE MIXED WITH THE OTHER GRAPHICS. ╘HESE PRIMITIVES CAN ALSO BE PUT INTO A MORE COLORFUL MODE, BUT YOU LOSE HALF OF THE RESOLUTION IN THAT PROCESS. ╔. ╙TANDARD ├HARACTER ─ISPLAY ═ODE ╔N THE CHARACTER DISPLAY MODE, ╓╔├ FETCHES CHARACTER POINTERS FROM VIDEO MATRIX, WHICH CONSISTS OF 1000 8-BIT BYTES FORMATTED AS 25 ROWS OF 40 CHARACTERS EACH. ╘HE 8-BIT CHARACTER CODE IMPLIES 256 DIFFERENT CHARACTERS SIMULTANEOUSLY ONSCREEN. ┼ACH CHARACTER CODE CAN HAVE AN UNIQUE IMAGE, WHICH CONSISTS OF 8 BYTES IN CHARACTER MEMORY. ╘HE POSITION OF THE CHARACTER MEMORY CAN BE MOVED WITH THE CHARACTER BASE POINTER AND THUS IT IS POSSIBLE TO HAVE SEVERAL CHARACTER SETS SIMULTANEOSLY IN MEMORY. ╧NE CHARACTER MEMORY IS 2048 BYTES. ╔N ADDITION TO THE CHARACTER CODE, EACH POSITION IN VIDEO MATRIX HAS AN ASSOCIATED COLOR NYBBLE (4 BITS) IN COLOR MEMORY ($─800-$─╞╞╞). ╞OR EACH ZERO-BIT IN THE CHARSET THE BACKGROUND COLOR FROM REGISTER $21 IS DISPLAYED, THE COLOR-NYBBLE IS USED FOR THE ONE-BIT. ╔╔. ├HARACTER ═ULTICOLOR ═ODE ╔N CHARACTER MULTICOLOR MODE, COLOR SELECTION IS INCREASED. ┼ACH BYTE IS FETCHED FROM THE CHARACTER MEMORY JUST LIKE IN THE STANDARD CHARACTER MODE, BUT THEY ARE INTERPRETED DIFFERENTLY. ╔N THIS MODE BYTES ARE DIVIDED INTO BIT-PAIRS. ╞OR BIT PAIR "00" THE BACKGROUND COLOR FROM REGISTER $21 IS DISPLAYED, BACKGROUND COLOR #1 IS USED FOR BIT PAIR "01" AND BACKGROUND COLOR #2 FOR BIT PAIR "10". ╘HE COLOR NYBBLE WILL DEFINE THE COLOR FOR BIT PAIR "11". ╘HE HIGHEST BIT IN THE COLOR MEMORY DEFINES WHETHER THE CHARACTER IS TO BE DISPLAYED IN MULTICOLOR ("1") OR IN STANDARD MODE ("0"). ┬ECAUSE OF THIS, ONLY COLORS IN THE RANGE FROM 0 TO 7 ARE POSSIBLE FOR BIT PAIR "11". ┴ND SINCE TWO BITS ARE REQUIRED TO SPECIFY ONE DOT COLOR, THE CHARACTER IS NOW DISPLAYED AS A 4X8 MATRIX INSTEAD OF THE 8X8 MATRIX AND THE SIZE OF THE DOTS ARE DOUBLED HORIZONTALLY. ╔╔╔. ┼XTENDED ├OLOR ═ODE ╘HE EXTENDED COLOR MODE ALLOWS THE SELECTION OF ONE BACKGROUND COLOR FROM FOUR POSSIBILITIES FOR EACH CHARACTER POSITION IN THE NORMAL 8X8 RESOLUTION. ╘HE CHARACTER IMAGE DATA IS PROCESSED LIKE IN STANDARD CHARACTER MODE, BUT THE TWO MOST SIGNIFICANT BITS IN THE CHARACTER CODE (VIDEO MATRIX) ARE USED TO SELECT THE RIGHT BACKGROUND COLOR REGISTER. ╧NLY CHARACTER IMAGES FROM 0 TO 63 ARE ACCESSIBLE, BECAUSE TWO OF THE MOST SIGNIFICANT BITS ARE USED FOR THE BACKGROUND COLOR SELECTION. ┼XTENDED COLOR MODE AND MULTICOLOR MODE SHOULD NOT BE SELECTED SIMULTANEOSLY, BECAUSE THIS WILL RESULT A BLACK SCREEN. ╚OWEVER, THIS IS A VERY EASY WAY TO HIDE SOMETHING IF NEEDED. ╔╓. ╙TANDARD ┬IT ═AP ═ODE ╔N BIT MAP MODE, A ONE-TO-ONE CORRESPONDENCE EXISTS BETWEEN EACH DISPLAYED DOT AND A MEMORY BIT. ╘HE BIT MAP PROVIDES A RESOLUTION OF 320╚ X 200╓ INDIVIDUALLY CONTROLLED PIXELS. ╘HE VIDEO MATRIX IS STILL ACCESSED AS IN CHARACTER MODE, BUT THE DATA IS INTERPRETED AS COLOR DATA. ╫HEN A BIT IS "0" IN THE BIT MAP DATA, THE COLOR FROM THE LOWER NYBBLE IS SELECTED. ╘HE HIGHER NYBBLE FROM THE VIDEO MATRIX IS USED FOR THE BIT "1". ╓. ═ULTICOLOR ┬IT ═AP ═ODE ╔N MULTICOLOR BIT MAP MODE TWO BITS IN THE BIT MAP MEMORY DETERMINE THE COLOR OF ONE PIXEL. ╔F THE BIT PAIR IS "11", THE COLOR FOUND FROM THE COLOR MEMORY IS USED. ╘HE BACKGROUND COLOR IS USED FOR BIT PAIR "00" AND THE VIDEO MATRIX DEFINES THE COLORS FOR BIT PAIRS "01" AND "10". ┴S IT TAKES TWO BITS TO DEFINE ONE PIXEL COLOR, THE HORIZAONTAL RESOLUTION IS HALVED TO 160╚ X 200╓. ╓╔. ═OVABLE ╧BJECT ┬LOCKS (═╧┬S) ╘HE MOVABLE OBJECT BLOCK IS A SPECIAL TYPE OF GRAPHICAL OBJECT WHICH CAN BE DISPLAYED INDEPENDENTLY FROM THE OTHER GRAPHICS. ┼ACH ONE OF THE ═╧┬S CAN BE MOVED INDEPENDENTLY ANYWHERE IN THE SCREEN. ┼IGHT UNIQUE ═╧┬S CAN BE DISPLAYED SIMULATANIOUSLY, EACH DEFINED BY 64 BYTES IN MEMORY WHICH ARE DISPLAYED AS A 24 X 21 PIXEL ARRAY. ┼ACH ═╧┬ CAN BE SELECTIVELY ENABLED (═N┼="1") OR DISABLED (═N┼="0"). ┴ ═╧┬ IS POSITIONED VIA ITS ╪ AND ┘ POSITION REGISTERS. ╬INE BITS ARE NEEDED TO DEFINE THE VERTICAL POSITION AND THE MOST SIGNIFICANT BITS OF ALL ═╧┬S ARE STORED IN THE REGISTER $10. ┴S ╪ LOCATIONS 23 TO 347 AND ┘ LOCATIONS 50 TO 249 ARE ENTIRELY VISIBLE ON THE SCREEN, ═╧┬S CAN BE SMOOTHLY MOVED TO AN OFF-SCREEN POSITION. ┼ACH ═╧┬ HAS ITS OWN COLOR REGISTER AND A ═╧┬ CAN BE DISPLAYED EITHER IN STANDARD OR MULTICOLOR MODE (═N═├="1"). ┴S USUALLY, MULTICOLOR MODE GIVES MORE COLORS, BUT HALVES THE HORIZONTAL RESOLUTION. ╔N MULTICOLOR MODE BIT PAIR "00" IS TRANSPARENT, THE ═╧┬ COLOR REGISTER DEFINES THE COLOR FOR PAIR "10", AND ═╧┬ MULTICOLOR REGISTERS GIVE THE COLORS FOR PAIRS "01" AND "11". ═╧┬S CAN BE SELECTIVELY EXPANDED IN BOTH DIRECTIONS. ╫HEN ═╧┬ IS EXPANDED, THE PIXEL SIZE ALSO EXPANDS AND IT IS STILL DISPLAYED AS 24 X 21 MATRIX (12 X 21 IN MULTICOLOR MODE). ═╧┬ PRIORITIES DEFINE WHETHER A ═╧┬ APPEARS BEHIND OR ON TOP OF THE CHARACTER OR BIT MAP GRAPHICS. ┴ "1" IN ═N─╨ MEANS ═╧┬ IS DISPLAYED BEHIND. ═╧┬ COLLISION REGISTERS MAY BE USED TO DETECT IF A NON-TRANSPARENT DATA OF TWO ═╧┬S OR A ═╧┬ AND CHARACTER OR BITMAP FOREGROUND DATA IS COLLIDING. [┼D'S ╬OTE: ═╧┬'S ARE ╙PRITES. ├OMMODORE INITIALLY REFERRED TO THEM AS ═╧┬'S AND STILL DOES IN SOME AREAS.] ╓╔╔. ╧THER FEATURES ╘HE DISPLAY SCREEN MAY BE BLANKED BY SETTING THE ─┼╬ BIT TO A "0". ╘HE ENTIRE SCREEN WILL BE FILLED WITH THE BORDER COLOR AS SET IN REGISTER 32 ($20). ╫HEN THE SCREEN IS BLANKED, ╓╔├ WILL NEED ONLY TRANSPARENT MEMORY CYCLES AND THE PROCESSOR IS NOT SLOWED DOWN. ╚OWEVER, ═╧┬ DATA IS STILL FETCHED, IF THE ═╧┬S ARE NOT ALSO DISABLED. ╘HE NORMAL DISPLAY CONSISTS OF 25 ROWS OF 40 CHARACTERS EACH. ╘HE DISPLAY WINDOW CAN BE REDUCED TO 24 ROWS AND 38 CHARACTERS. ╘HIS HAS NO EFFECT ON HOW THE DATA IS INTERPRETED, ONLY THE CHARACTERS NEXT TO THE BORDER ARE COVERED BY THE BORDER. ╥╙┼╠ CONTROLS THE NUMBER OF ROWS ("1" FOR 25 ROWS) AND ├╙┼╠ CONTROLS THE NUMBER OF COLUMNS ("1" FOR 40 COLUMNS). ╘HE DISPLAY DATA MAY BE SCROLLED UP TO ONE CHARACTER SPACE IN BOTH VERTICAL AND HORIZONTAL DIRECTION. ╨OSITION OF THE SCREEN IS SET WITH THE 3 LOWEST ORDER (LEAST SIGNIFICANT) BITS IN REGISTERS 22 ($16) AND 17 ($11). ╠IGHT PEN LATCH IS USED TO CATCH THE POSITION OF THE LIGHT PEN WHEN A PULSE IS RECEIVED IN THE ╠╨ PIN. ╘HE VALUE IS LATCHED ONLY ONCE IN A FRAME. ╘HE RASTER REGISTER IS A DUAL-FUNCTION REGISTER. ┴ READ FROM THE RASTER REGISTER RETURNS THE CURRENT RASTER POSITION AND A WRITE TO IT WILL SET THE RASTER COMPARE VALUE. ╫HEN THE WRITTEN VALUE AND THE CURRENT RASTER LINE