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═ACHINE ╠ANGUAGE ═ADE ┼ASY ! (╨ART 1) BY ╠YLE ╟IESE ─┼╠╨╚╔ ═AIL: ╠┘╠┼╟ ╘HIS IS THE FIRST IN A SERIES OF COLUMNS TO HELP EASE THE NEWCOMER INTO THE WORLD OF ═ACHINE ╠ANGUAGE. ╔ AM STILL NOT SURE HOW ╔ GOT INTO THIS JOB, BUT ╔ WILL GIVE IT MY BEST! ╔T IS QUITE HARD TO GET STARTED IN ═ACHINE ╠ANGUAGE PROGRAMING, BUT JUST LIKE THE ┬┴╙╔├ IN YOUR FIRST COMPUTER, ONCE YOU KNOW A LITTLE ABOUT IT IS NOT THAT DIFFICULT. ╘HIS COLUMN WILL BE BASED ON THE 6502 & 6510 MICROPROCESSORS THAT ARE USED IN THE ├OMMODORE 64 & ╓IC-20, ┴TARI 400-600-800 SERIES MACHINES, AND IN SOME ┴PPLES. ╘HE 8500 PROCESSOR IN THE ├-128 IS A DIRECT COUSIN OF THE 6502. ┴LL INSTRUCTIONS FOR THE 6502 WILL DO THE SAME THINGS ON THE 8500. ╘HE 8500 CAN DO MORE, BUT THAT WILL NOT BE COVERED HERE. ╔N STARTING OUT WITH ANYTHING THAT IS FOREIGN, IT TAKES TIME TO COVER ALL THE TERMINOLGY NEEDED TO UNDERSTAND THE SIMPLEST INSTRUCTION. ╙O, THIS MONTH'S COLUMN WILL BE COVERING JUST THAT, TERMINOLOGY. ╔ GOT MY 'TRAINING' IN ═ACHINE ╠ANGUAGE BY FIRST READING ╥ICHARD ═ANSFIELD'S BOOK "═ACHINE ╠ANGUAGE FOR ┬EGINNERS". ╔T IS, IN MY OPINION, AN EXCELLENT BOOK FOR THE NOVICE. ╔ CANNOT, HOWEVER, COMMENT ON HIS SECOND BOOK AS ╔ HAVE NOT READ IT. ┴ BOOK THAT IS ON THE ═╒╙╘ HAVE LIST FOR THE ├-64 OWNER IS THE '╨ROGRAMMERS ╥EFERENCE ╟UIDE' (╨╥╟). ╔T HAS VALUABLE INFORMATION ON HOW TO USE THE ╦ERNAL ROUTINES INSIDE THE ├-64. ╠ATER, ╔ HOPE TO COVER HOW TO READ THE ╦ERNAL ROUTINE CHARTS IN THE ╨╥╟. ═EMORY MAPS OF THE COMPUTER YOU ARE USING ARE INVALUABLE! ╘WO GOOD ONES FOR THE ├-64 ARE "╘HE ┴NATOMY OF THE ├OMMODORE 64", FROM ┴BACUS ╙OFTWARE, AND "═APPING THE ├-64" BY ╙HELDON ╠EEMAN, FROM ├OMPUTE! ╨UBLICATIONS. "╘HE ┴NATOMY OF THE ├OMMODORE 64" HAS VERY GOOD DISASEMBLIES OF ALL THE ╥╧═ ROUTINES IN THE 64. ╙HELDON'S BOOK IS A GOOD REFERENCE FOR THE LOW MEMORY USAGE IN THE 64 AND FOR SOME COMMENTS ON ┬┴╙╔├ AND THE ╦┼╥╬┴╠. ┘OU WILL ALSO NEED A SIMPLE ASSEMBLER AND A SIMPLE DISSAMBLER TO USE. ╘HERE ARE GOOD ╨UBLIC ─OMAIN ONES HERE IN THE DATABASE OF THE ╞LAGSHIP. ╠ATER, IF YOU WANT TO GET MORE INVOLVED IN ═ACHINE ╠ANGUAGE, YOU WILL WANT A MORE COMPLEX ASSEMBLER. ┬UT AGAIN, THAT IS A TOPIC FOR FUTURE COLUMN. ═┼═╧╥┘. ╘HAT IS THE STUFF WE WANT MORE AND MORE OF! ┬UT WHAT IS MEMORY? ═EMORY, IN ITS SIMPLEST FORM, IS CALLED A "BIT." ├OMMON BELIEF HAS IT THAT THE TERM BIT IS SHORT FOR BINARY DIGIT, AND GOT ITS NAME FROM THAT. ┴ BINARY DIGIT HAS ONLY TWO STATES, A ZERO OR A ONE. ╬OT MUCH POWER OR INFORMATION CAN BE STORED IN ONE OF TWO DIGITS! ┬Y CHAINING THE BITS IN A LOGICAL MANNER, WE CAN USE THEM TO STORE MORE INFORMATION. ╘HE NEXT BUILDING BLOCK WE USE IS A BYTE. ┴ BYTE IS 8 BITS OF MEMORY USED TOGETHER. ╫ITH 8 BITS, WE HAVE 256 DIFFERENT COMBINATIONS OF ONE'S AND ZERO'S TO WORK WITH. ╥ICHARD ═ANSFIELD USED AN EXCELLENT ANALOGY TO EXPLAIN HOW MEMORY IS CONFIGURED. ╔MAGINE THE 8 BITS AS 8 LIGHTS IN A HOUSE. ╘HE LIGHTS WILL BE ON OR OFF AS THE BITS ARE TURNED ON OR OFF. ╬OW, LINE UP NUMBER OF HOUSES IN A ROW DOWN A LONG STREET. ╘HE FIRST HOUSE WILL HAVE AN ADDRESS OF ZERO. ╘HE SECOND ONE AN ADDRESS OF 1 AND SO ON, UNTIL WE GET TO THE END OF OUR STREET (MEMORY). ╧N THE 64 THE END WILL BE AT 64╦. ╘HAT IS NOT 64,000. ┴ ╦ OF MEMORY IS 1024. ╘HAT NUMBER IS USED PARTLY BECAUSE IT IS A FACTOR OF 2 (2 TO THE POWER OF 10). ╘HIS MEANS THE LAST HOUSE IN MEMORY WILL HAVE AN ADDRESS OF 65,535 (REMEMBER THAT WE STARTED WITH AN ADDRESS OF ZERO). ╥EMEMBER, ╔ SAID THAT A BYTE CAN HOLD 256 DIFFERENT BIT COMBINATIONS? ╙INCE THAT IS WHAT A BYTE CAN HANDLE, MEMORY IS AGAIN DIVIDED INTO 256 BYTE CHUNKS, OR BLOCKS ON OUR STREET, CALLED PAGES. ┌ERO PAGE, BESIDES BEING THE FIRST PAGE, IS SPECIAL. ┬ECAUSE THE PAGE IS ZERO, THE MICROPROCCESSOR IS SET UP TO BE ABLE TO ACCESS ZERO PAGE FASTER. ╘HE REASON IS THAT IN ORDER TO ACCESS MEMORY WE HAVE TO USE THE ADDRESS OF THE BYTE OF MEMORY. ╘HE ADDRESS IS DIVIDED INTO TWO BYTES CALLED THE "LEAST SIGNIFICANT BYTE" (╠╙┬) AND THE "MOST SIGNIFICANT BYTE" (═╙┬). ╫HEN TALKING ABOUT THE BYTES IN ZERO PAGE, THE ═╙┬ WILL BE ZERO. ╙O A SPECIAL SET OF INSTRUCTIONS WERE SET UP INSIDE THE 6502 TO WORK WITH ZERO PAGE. ╘HESE INSTRUCTIONS WORK FASTER BECAUSE THE PROCESSOR FETCHES ONE LESS BYTE IN ORDER TO FIND THE ADDRESS. ╘HAT FACT WAS NOT LOST ON ├OMMODORE WHEN THEY DESIGNED THEIR COMPUTERS. ╘HEY MADE HEAVY USE OF ZERO PAGE. ┴NOTHER THING THAT YOU WILL FIND IS THE HEAVY USE OF ╚EXIDECIMAL NOTATION. ╘HIS IS A NUMBERING SYSTEM BASED ON 16 DIGITS INSTEAD OF 10 USED IN DECIMAL THAT WE ARE USED TO. ╚EXIDECIMAL, OR HEX FOR SHORT, USES 0-9, AND ┴-╞ FOR ITS DIGITS, WITH ┴=10, ┬=11, ETC. ╚EX IS NORMALLY PREFIXED BY A "$" AS $10, WHICH IS 16 IN DECIMAL. ╔T IS SOMETIMES WRITTEN AS 10H, BUT THAT IS SELDOM SEEN ANYMORE. ╚EX IS CONVENIENT FOR USE WITH BYTE SIZED MEMORY AS 2 DIGITS ARE ALL THAT ARE NEEDED TO SHOW THE MAXIMUM VALUE THAT A BYTE CAN HOLD (RANGING FROM $00 TO $╞╞(255)). ╞OUR DIGITS ARE ALL THAT ARE NEEDED TO DESIGNATE MEMORY LOCATIONS IN A 64K MACHINE. ╘HAT IS TWO BYTES CAN RANGE FROM $0000 TO $╞╞╞╞ ( OR 65,535). ╔ STRONGLY SUGGEST THAT YOU BECOME FAMILAR WITH HEX AS IT IS USED OFTEN IN ARTICLES OR BOOKS WRITTEN ABOUT ═╠. ╘HE HEX DESIGNATION FOR MEMORY LOCATIONS CAN BE SPLIT VERY EASILY. ╔N THE EXAMPLE ABOVE, $╞╞╞╞, THE ╠╙┬ WILL HOLD $╞╞ AND THE ═╙┬ WILL HOLD $╞╞. ╬OTE: THE ═╙┬ ALSO REFERS TO THE PAGE NUMBER WHEN TALKING ABOUT MEMORY LOCATIONS. ┴T THIS POINT, YOU HAVE TO KNOW SOMETHING ABOUT WHAT IS INSIDE YOUR MICROPROCESSOR. ╘HERE IS A LITTLE ╥ANDOM ┴CCESS ═EMORY (╥┴═) AND THE INSTRUCTIONS, CONTAINED IN ╥EAD ╧NLY ═EMORY (╥╧═)-LIKE MEMORY. ╘HE ╥┴═ MEMORY IS DIVIDED INTO 'REGISTERS': THE ┴ REGISTER, COMMONLY CALLED THE ┴CCUMLATOR; ╪ REGISTER; ┘ REGISTER] ╙TACK ╨OINTER (╙╨); ╨ROGRAM COUNTER (╨├); AND THE ╙TATUS ╥EGISTER (╙╥), LSO CALLED THE ╨ REGISTER. ┼ACH REGISTER HAS ITS OWN SPECIAL PROPERITIES AND/OR FUNCTIONS THAT ENABLE IT TO DO CERTAIN TASKS THAT OTHER REGISTERS CANNOT DO. ╔ WILL BE USING THE TERM 6502 EVEN THOUGH EVERYTHING APPLIES EQUALLY TO THE 6510 AND 8500 UNLESS OTHERWISE NOTED. ╘HE ┴ REG IS WHERE ALL THE MATH FUNCTIPMS OF THE 6502 ARE DONE. ╔N ORDER TO ADD, SUBTRACT, OR DO LOGICAL FUNCTIONS, ONE NUMBER HAS TO BE IN THE ACCUMLATOR. ╘HE ╪ ND ┘ REGISTERS ARE USE FOR INEXING, BUT THEY DO HAVE SOME DIFFERENT PROPORTIES. ╘HE DIFFERENCES RE SUBTLE AND ╔ WILL COVER THEM IN A LATER COLUMN. ╘HE ╨├ IS USED TO KEEP TRACK OF WHERE WE ARE IN THE PROGRAM SO THAT THE 6502 WILL KNOW WHERE TO GET ITS NEXT INSTRUCTION. ╘HE ╙╨ IS A POINTER TO THE ╙TACK IN MEMORY. ╘HIS IS USED TO STORE THE RETURN ADDRESS WHEN YOU ╩╙╥ (╩UMP WITH ╥ETURN - SIMILAR TO ╟╧╙╒┬ IN ┬┴╙╔├). ╘HE STACK MAY ALSO BE USED FOR TEMPORARY STORAGE, BUT THIS APPLICAIONT SHOULD BE LEFT TO ADVANCED PROGRAMMERS. ╘HE ╨ REG, OR ╙TATUS ╥EG, IS USED TO KEEP TRACK OF CERTAIN CONDITIONS THAT HAPPENED IN THE LAST OPERATION. ─ID THE LAST OPERATION RESULT IN A ZERO RESULT? ─ID THE LAST ADDITION CAUSE A CARRY? ─ID THE LAST SUBTRACTION USE A BORROW? ╔N THE ╨ REG, 7 FLAGS THAT ARE USED FOR THIS PURPOSE. ╔ WILL COVER THEM IN A LATER COLUMN. ╫ITH AN ARTICLE ON ANYTHING NEW, IT IS VERY HELPFUL TO SHOW A WORKING EXAMPLE. ═╠ IS NO EXCEPTION TO THAT RULE. ╔N THIS VAIN ╔ THOUGHT WE WOULD DO SOMETHING SIMPLE, CHANGE THE COLOR MEMORY ON THE ├-64. ╔N CASE SOME OF YOU HAVE FORGOTTEN IN THE ╓ERSION2 ╦ERNAL ├-64 A CLEAR SCREEN CAUSED THE 64 TO SET THE BACKGROUND COLOR MEMORY TO THE CURRENT FOREGROUND COLOR. ╙O IF THEN YOU WANTED TO POKE TO THE SCREEN, YOU COULDN'T SEE IT AS THE CHARACTER WAS THE SAME COLOR AS THE FOREGROUND. ╫E WOULD NEED TO FILL COLOR MEMORY WITH SOMETHING OTHER THAN THE FOREGROUND COLOR. ╧N THE 64 THE DEFAULT FOREGROUND COLOR IS BLUE, WHICH HAS A COLOR NUMBER OF 6. ╫E NEED TO CHANGE IT TO SOME OTHER NUMBER. ╫E COULD DO THAT IN ┬┴╙╔├ WITH A FOR-NEXT LOOP BUT THAT TAKES MUCH TOO LONG. ╔N ═╠ IT IS A SHORT AND SIMPLE OPERATION. ╫ITH THIS EXAMPLE, ╔ WILL USE THE CONVECTIONS USED WITH ╙UPERMON. ╘HAT PROGRAM IS IN THE ╨─ AND WAS INCLUDED ON THE DISK BONUS PACK INSIDE THE 1541. ╙O WE WILL START THIS PROJECT BY LOADING AND RUNNING ╙UPERMON(MOST OTHER SIMPLE MONITORS USE VERY SIMULAR SYNTAX). ╘HE FIRST THING YOU WILL SEE IS A STATUS LINE. ╘HAT SHOWS YOU THE CONTENTS OF ALL THE 6502 REGISTERS, STARTING WITH THE ╨ROGRAM COUNTER(╨├), ╔╥╤ VECTOR(THIS ARE THE ROUTINES THAT SERVICE THE KEYBOARD AND ╘╧─ CLOCKS AND OTHER THINGS AND OCCURS APPROX EVERY 60TH OF A SECOND), THE ╙TATUS ╥EG(╙╥ ALSO CALLED THE ╨ REG), THE ┴ REG(OR ┴CCUMLATOR, THE ╪ REG, THE ┘ REG AND THE ╙TACK POINTER. ╘HEN A PERIOD ON THE NEXT LINE. ╘HE PERIOD REPLACES THE CURSOR. ╚ERS'S A PRINTOUT OF OUR PROGRAM AND ╔ WILL EXPLAIN. .┴ ├000 ╠─┘ #$─8 .┴ ├002 ╙╘┘ $╞╞ .┴ ├004 ╠─┘ #$00 .┴ ├004 ╙╘┘ $╞┼ .┴ ├006 ╙╘┘ $╞┼ .┴ ├008 ╠─┴ #$00 .┴ ├00┴ ╙╘┴ ($╞┼),┘ .┴ ├00├ ╔╬┘ .┴ ├00─ ┬╬┼ $├00┴ .┴ ├00╞ ╔╬├ $╞╞ .┴ ├011 ╠─┴ $╞╞ .┴ ├013 ├═╨ #$─├ .┴ ├015 ┬╬┼ $├008 .┴ ├017 ╥╘╙ .┴ ├018 ┴FTER THE PERIOD, WE TYPE AN ┴. ╘HIS TELLS THE PROGRAM TO START ASSEMBLING WANT WE TYPE IN. ╬EXT WE TYPE IN THE STARTING ADDRESS IN ╚┼╪. ╔N THIS EXAMPLE WE USE $├000, WHICH IS 49152 DECIMAL. ╘HIS A FREE ZONE THAT ┬┴╙╔├ DOES USE AND IS QUITE FREQUENTLY USED FOR ═╠ SUBROUTINES AND PROGRAMS, LIKE ├┬═'S ╫EDGE PROGRAM. ╬EXT(WE ARE STILL ON THE FIRST LINE) WE TYPE IN THE MNEMONIC FOR THE INSTRUCTION WE WANT EXICUTED. ╔N THIS CASE THE ╧P CODE IS ╠─┘ WHICH MEANS ╠OA─ THE ┘ REG. ╘HE #$─8 IS CALLED THE ARUGMENT. ╘HE '#' USE THE NUMBER THAT FOLLOWS(AS OPPSED TO TREATING IT AS AN ADDRESS). ╙O IT IS TELLING US TO ╠OA─ THE ┘ REG WITH THE NUMBER $─8. ╘HIS METHOD OF ADRESSING IS CALLED IMMEDIATE. ╬OW WE PRESS THE <├╥> AND YOU HAVE PUT YOUR FIRST INSTRUCTION INTO MEMORY! ┴FTER THE <├╥> THE COMPUTER WILL RESPOND WITH '.┴ ├002'. ┴FTER YOU GIVE THE ASSEMBLER THE START ADDRESS IT WILL FIGURE OUT WHERE THE NEXT INSTRUCTION GOES FOR YOU. ╔F THIS WAS THE END OF THE PROGRAM WE WOULD JUST ANSWER BY TYPING A <├╥>. ╘HE SECOND OP CODE IS ╙TORE ╘HE ┘ REG. ╬OW ALL THE STORE AND LOAD INSTRUCTIONS ACTUALLY COPY THE INFORMATION FROM ONE PLACE TO ANOTHER WITHOUT DESTROYING THE ORIGNAL. ╙O IN THIS CASE (WITHOUT THE '#' MEANS THAT WE TREAT THE ARGUMENT AS AN ADDRE SS) WE WILL STORE (OR COPY) THE CONTENTS OF THE ┘ REG INTO MEMORY LOCATION $╞┼. ┬Y THE WAY THIS ADDRESSING MODE IS CALLED ZERO PAGE ABSOLUTE, ABSOLUTE BECAUSE WE ARE SPECIFING THE EXACT ADRESS TO USE AND ZERO PAGE BECAUSE THE ADDRESS IS IN ZERO PAGE. ╘HE NEXT TWO INSTRUCTIONS ARE THE SAME AS ABOVE EXCEPT WE WILL PUT $00 INTO MEMORY LOCATION $╞┼. ╔N CASE YOU HAVE NOT NOTICED WE HAVE PUT ADDRESS $─800 INTO $╞┼ & $╞╞. ╘HE ADRESS $─800 IS THE START OF COLOR MEMORY AT 55296 DECIMAL. ┬UT ╚┼┘ ╫AIT ┴ ═INUTE!!! ─IDN'T YOU JUST PUT THE ADRESS IN BACKWARDS?? ┘ES WE DID BUT THAT IS THE WAY THE 6502 EXPECTS TO FIND ALL OF ITS ADRESS. ╠╙┬ FIRST THEN THE ═╙┬. ╔ DON'T KNOW WHY BUT THAT IS THE WAY IT IS IN THE 6502, ADRESSES ARE STORED IN MEMORY BACKWARDS. ╘HE NEXT INSTRUCTION TELLS US TO ╠OA─ THE ┴ REG WITH SOMETHING. ╘HE ARGUMENT TELLS WHAT. ╔N THIS CASE THE '#' AGAIN TELLS US TO USE THIS NUMBER AND NOT TREAT IT AS AN ADDRESS. ┬Y THE WAY THIS IS CALLED THE IMMEDIATE ADDRESSING MODE. ╙O WE PUT THE NUMBER $01 INTO THE ┴ REG, WHICH IS THE COLOR NUMBER FOR WHITE. ┬Y CHANGING THIS NUMBER WE COULD FILL COLOR MEMORY WITH ANY OF THE 16(0-15) COLORS. ╬OW WE WANT TO PUT THE COLOR NUMBER INTO THE COLOR MEMORY. ╘HIS NEXT INSTRUCTION DOES THAT FOR US. ╫E ARE GOING TO ╙╘ORE THE ┴ REG, BUT WHERE? ╫ELL, THE PRENTHASIS AROUND THE $╞┼ TELLS US THAT $╞┼ IS NOT THE TARGET ADRESS BUT THAT WE WILL FIND THE TARGET CONTAINED IN MEMORY LOCATIONS $╞┼ & $╞╞(WHICH WE SET TO $─800 EARLIER). ╬OW WHAT DO WE DO WITH THE ',┘"? ╫E TAKE THE ADRESS FOUND AT $╞┼ & $╞╞( $─800) AND ADD THE ┘ REG TO IT. ╘HE FIRST TIME THROUGH THIS ROUTINE THE ┘ REG CONTAINS $00. ╙O WE WILL ╙╘ORE THE ┴ REG AT $─800+0 OR AT $─800. ╘HIS IS A VERY USEFUL ADRESSING MODE CALLED INDIRECT ┘, YOU WILL USE IT OFTEN! ╔N THE NEXT INSTRUCTION, WE ╔╬CREMENT THE ┘ REG OR ADD 1 TO IT. ╘HIS ADRESSING MODE IS CALLED IMPLIED. ╔ GUESS IT GOT ITS NAME BECAUSE THE ARGUMENT DOES NOT NEED TO BE SPECIFIED OR IS IMPLIED. ╘HE NEXT INSTRUCTION IS AN IMPORTANT ONE. ╔T STANDS FOR ┬RANCH IF ╬OT ┼QUAL. ╬OT EQUAL TO WHAT? ╫ELL THE INSTRUCTION CHECKS THE ┌ERO FLAG IN THE ╙TATUS REG. ╫HEN THE PREVIOUS INSTRUCTION (IN THIS CASE ╔╬┘) RESULTS IN A ZERO RESULT OR EQUALS THE ZERO FLAG IS SET IN THE ╙TATUS REG. ╔F WE JUST KEEP INCREMENT THE ┘ REG, HOW WILL THAT EVER BE EQUAL TO ZERO? ╟OOD QUESTION! ┼ARLIER IN THIS COLUMN ╔ STATED THAT A BYTE COULD ONLY HOLD A NUMBER FROM $00-$╞╞(255). ╘HE REGISTERS IN THE 6502 ARE ONLY 1 BYTE LONG, EXCEPT THE ╨├ WHICH IS 2 BYTES LONG. ╙O WHAT HAPPENS WHEN THE ┘ REG HOLDS $╞╞(255) AND WE INCREMENT OR ADD ONE TO IT? ╔T CANN'T HOLD A BIGGER NUMBER, SO IT ROLLS OVER TO $00, BUT WHEN THAT HAPPENS IT SETS THE ZERO FLAG IN THE ╙TATUS REG. ┬ACK TO THE INSTRUCTION ┬RANCH IF ╬OT ┼QUAL TO ZERO. ╔F THE ┘ REG IS NOT ZERO THEN WE GO BACK TO $├00┴. ╬OW THE ┘ REG HOLDS A $01 AND WE WILL ADD THE ADDRESS FOUND AT $╞┼-$╞╞ TO THE CONTENTS OF THE ┘ REG AND GET $─800+1 OR $─801. ╙O THE CONTENTS OF THE ┴ REG IS NOW COPYED INTO $─801 OR THE SECOND BYTE IN COLOR MEMORY. ╘HIS OF COURSE CONTINUES UNTIL THE ┘ REG ROLLS OVER TO ZERO. ╘HEN YOU FALL THROUGH TO $├00╞. ╘HE INSTRUCTION THERE IS ╔╬├REMENT (NO '#') THE NUMBER IN MEMORY LOCATION $╞╞. ╘HEN WE WILL ╠OA─ THE ┴ REG WITH THAT VALUE. ╘HE FIRST TIME WE HIT THIS WE WILL BE GOING FROM $─8 TO $─9. ╬OW THAT WE HAVE THAT VALUE IN THE ┴ REG WE CAN ├O═╨ARE IT TO SOMETHING, ( ╬OTE THE '#' WHICH MEANS THAT WE COMPARE TO THE NUMBER $─├ NOT MEMORY LOCATION $─├). ╫HY $─├? ╘HAT'S ABOVE OUR COLOR MEMORY. ╫HEN WE ARE AT $─┬, WE STILL HAVE SOME OF OUR COLOR MEMORY THERE AND NEED TO FILL IT UP WITH OUR COLOR NUMBER. ╘HE NEXT INSTRUCTION IS THE ┬RANCH IF ╬OT ┼QUAL, WHICH AGAIN CHECKS THE ZERO FLAG. ╘HIS TIME THE ZERO FLAG WAS SET OR NOT SET ACCORDING TO THE OUTCOME OF THE ├O═╨ARE INSTRUCTION AT $├013. ─URING THAT COMPARE IF THE ┴ REG CONTAINED THE NUMBER $─├ THEN THE ZERO FLAG WAS SET, TELLING THAT THEY WERE EQUAL. ┴ND THE LAST INSTRUCTION IS ╥E╘URN FOR ╙UBROUTINE. ╘HIS IS JUST LIKE THE RETURN FOUND IN ┬┴╙╔├. ╫HAT DO WE DO KNOW? ╘HE COMPUTER ASKED ME TO ASSEMBLE AN INSTRUCTION AT $├018. ╫E TELL THE ASSEMBLER IN ╙UPERMON THAT WE ARE DONE BY A <├╥> ALONE. ╬OW HOW DO WE RUN THE PROGRAM? ╔T IS IN MEMORY THAT IS NOT DIRECTLY USED BY ┬┴╙╔├ AND BESIDES IT IS NOT A ┬┴╙╔├ PROGRAM! ╫ELL, THERE ARE TWO WAYS TO DO THAT AT THIS POINT. ╘HE FIRST ONE IS AFTER THE PERIOD TO TYPE '╟'(FOR ╟O) AND ├000<├╥>. ╘HAT TELLS ╙UPERMON TO GO TO $├000(WHICH IS WHERE WE PUT OUR PROGRAM) AND TRY TO EXECUTE OUR INSTRUCTIONS THERE.(╔ EMPHSIZE TRY BECAUSE SOMETIMES TYPING ERRORS DO HAPPEN!). ╘HE OTHER WAY IS TO EXIT TO ┬┴╙╔├ BY TYPE '╪' AT THE PERIOD, WHICH E╪ITS THE MONITOR AND RETURNS US TO ┬┴╙╔├. ╘HEN '╙┘╙49152'. ╘HIS TELLS ┬┴╙╔├ TO TRY TO EXECUTE THE ═╠ PROGRAM WE PUT AT $├000. ┴ND IF ALL WENT WELL, ALL OF OUR LETTERS ON THE SCREEN WILL TURN WHITE AND THE PROMPT '╥┼┴─┘' WILL APEAR(OR A PERIOD IF WE WERE STILL IN ╙UPERMON). ╫ELL, THAT'S ALOT OT DIGEST AND ╔ HOPE ╔ DIDN'T LOSE ANYONE, BUT IF YOU DID GET LOST ALONG SEND ME A NOTE AND ╔ WILL TRY TO SORT IT OUT FOR YOU!