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" " " " " " " " " " " " " ============================================ " ┴ ╥ ├ " -------------------------------------------- " ├╧══╧─╧╥┼ 64 ╞╔╠┼ ┴╥├╚╔╓┼ ╒╘╔╠╔╘┘ " ============================================ " " " " " " " " " " " ╥ELEASE 2.XX - ╙EPT 86 " " " " " " " " " " " -------------------------------------------- " ╘HIS ╓ERSION OF THE ┴╥├ ╒SER ╟UIDE " PREPARED FOR ┴MPERE ═ETAL BY " DRPCS " -------------------------------------------- " (├) ├OPYRIGHT 1986 - ┴MPERE ═ETAL " ┴LL ╥IGHTS ╥ESERVED " -------------------------------------------- " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " " "╔═╨╧╥╘┴╬╘ ╬╧╘╔├┼: ─UE TO THE METHODS EMPLOYED IN THE PRODUCTION "OF, AND SUBSEQUENT ACCESS TO, THE DATA THAT IS IN THIS DOCUMENT, "IT IS NOT POSSIBLE TO PRINT THE DOUBLE-QUOTES CHARACTER CHR$(34). "╙EVERAL EXAMPLES OCCUR HEREIN WHICH REQUIRE THE USER TO INPUT "COMMANDS AND TEXT FROM THE KEYBOARD, AND SOME OF THOSE EXERCISES "REQUIRE USING THE DOUBLE-QUOTES CHARACTER (THE ╙╚╔╞╘ED '2' KEY). " "╫HEN YOU SEE INSTRUCTION IN THE GUIDE THAT SHOWS ╘╫╧ APOSTROPHE "CHARACTERS TOGETHER, IT SHOULD BE INTERPRETED INSTEAD AS BEING "╧╬┼ DOUBLE-QUOTES CHARACTER ┴╬─ ╬╧╘ TWO SINGLE QUOTE CHARACTERS "(UNLESS OTHERWISE SPECIFIED). ╞OR EXAMPLE: " " ╘YPE: LOAD''*'',8,1 " "╘HIS SHOULD BE INTERPRETED AS: TYPE THE LETTERS ╠ ╧ ┴ ─; THEN "TYPE THE DOUBLE-QUOTES (THE ╙╚╔╞╘ED '2' KEY); THEN TYPE THE "ASTERISK; THEN TYPE THE DOUBLE-QUOTES, THE ├╧══┴, THE ─╔╟╔╘ '8', "ANOTHER ├╧══┴, AND FINALLY THE DIGIT '1'. " " " " " " " " " " " " " " " " " " " " "╘ABLE OF ├ONTENTS " ╘┴┬╠┼ ╧╞ ├╧╬╘┼╬╘╙ " ================= " " " ╔╬╘╥╧─╒├╘╔╧╬ .................................. 5 " " ╞REEWARE .................................. 5 " ─ISCLAIMER ................................ 6 " ╒PDATES ................................... 7 " ╓ERSION ╬UMBERS ........................... 7 " ┬UGS IN ┴╥├ ............................... 8 " ╔NTRO TO ┴╥├ .............................. 9 " ─RIVE ╠ETTERS ............................. 10 " " " ╟┼╬┼╥┴╠ ─╧╙ ├╧══┴╬─╙ .......................... 12 " " ╙ET ─EFAULT ─RIVE ......................... 12 " ┼XECUTE ╨ROGRAM ........................... 12 " ╙ET ─ATE .................................. 12 " ╓IEWING A ─ISK ─IRECTORY .................. 12 " ╙CRATCHING ╞ILES .......................... 13 " ═OVING ╞ILES ┬ETWEEN ─RIVES ............... 13 " ╥ENAMING ╞ILES ............................ 13 " ╓IEWING A ╞ILE'S ├ONTENTS ................. 13 " ─╧╙ ╫EDGE ................................. 14 " ╙IZE ...................................... 14 " ╙TART ..................................... 14 " " " ┼─╔╘╧╥ ├╧══┴╬─╙ ............................... 15 " " ╙ELECTING ╘┼╪╘ OR ┬┴╙╔├ ═ODE .............. 14 " ┴UTOMATIC ╠INE ╬UMBERING .................. 15 " ╥┼╙┼╘ ╘HE ├OMPUTER ........................ 15 " ├HANGE .................................... 15 " ─ELETE ╠INES .............................. 15 " ╞IND ╘EXT ................................. 15 " ╠OAD ╙EQUENTIAL ╞ILE ...................... 15 " ─ISABLE ┴╥├ ............................... 16 " ╥ENUMBER ╠INES ............................ 16 " ╙AVE ╙EQUENTIAL ╞ILE ...................... 16 " ╥EPEAT/╧FF ................................ 16 " ╒N-╬┼╫ (╧╠─) .............................. 16 " ╚EX TO ─ECIMAL ├ONVERSIONS ................ 16 " " " ┴╥├ ........................................... 17 " " ├REATING ┴RCHIVES ......................... 17 " ┴PPENDING TO ┼XISTING ┴RCHIVES ............ 17 " ╬OTES ON ╪═╧─┼═ ........................... 18 " ┼XTRACTING ╞ILES ╞ROM AN ┴RCHIVE .......... 18 " ┴RCHIVE ─IRECTORIES ....................... 19 " ╘YPING A ╞ILE IN AN ┴RCHIVE ............... 20 " ╨RINTER ╙ETUP ............................. 20 " ╓ERIFYING AN ┴RCHIVE ...................... 20 "╘ABLE OF ├ONTENTS " ╘┴┬╠┼ ╧╞ ├╧╬╘┼╬╘╙ (CONTINUED) " ============================== " " " ═┼═╧╥┘ ═┴╨ .................................... 21 " " " ╘╚┼╧╥┘ ╧╞ ╧╨┼╥┴╘╔╧╬ ........................... 21 " " ╥UN ╠ENGTH ├ODING (╨ACKING) ............... 21 " ╚UFFMAN ├ODING (╙QUEEZING) ................ 22 " ╙QUEEZE ┼XAMPLE ........................... 22 " ╠EMPEL ┌EV ├OMPRESSION (├RUNCHING) ........ 26 " ├RUNCH ┼XAMPLE ............................ 26 " " " ┴╥├╚╔╓┼ ╞╔╠┼ ╞╧╥═┴╘ ........................... 29 " " ╘HE ╚EADER ................................ 29 " ╙TORED ╞ILES .............................. 29 " ╨ACKED ╞ILES .............................. 30 " ╙QUEEZED OR ╙QUASHED ╞ILES ................ 30 " ├RUNCHED ╞ILES ............................ 30 " " " ┴╥├ ╨╥╧╟╥┴═ ╞╠╧╫ .............................. 31 " " ┴╥├ ....................................... 31 " ├REATE ┴RCHIVE ............................ 32 " ┴NALYZE THE ╞ILE .......................... 32 " ├OMPRESS THE ╞ILE ......................... 33 " ┼XTRACT THE ┴RCHIVE ....................... 33 " ┼XTRACT A ╞ILE ............................ 34 " ╞IX ╪═╧─┼═ ╨ADDING ........................ 35 " " " ┴╥├ ╘╥╔├╦╙ ┴╬─ ╘╔╨╙ ........................... 35 " " ═ANIPULATING ┴RCHIVES ..................... 35 " ╥ANDOM ┴CCESS ┴RCHIVES .................... 35 " ├HOOSING ╘HE ├OMPRESSOR ═ANUALLY .......... 36 " " " " " " " " " " " " " " " " "╞REEWARE "╞╥┼┼╫┴╥┼ " "╒SER-SUPPORTED SOFTWARE, OR ╞╥┼┼╫┴╥┼, IS AN ATTEMPT TO BYPASS "NORMAL MARKET CHANNELS THEREBY ALLOWING INDEPENDANT SOFTWARE "AUTHORS TO ENTER THE MARKET WITHOUT THE HIGH COST OF CONVENTIONAL "ADVERTISING AND PROMOTION. ┘OU BENEFIT BY HAVING THESE SAVINGS "PASSED ON TO YOU, AND WE BENEFIT BY NOT HAVING TO INVEST IN "COSTLY ADVERTISING, FANCY MANUALS AND PACKAGING. ┴FTER ALL, IF "THE SOFTWARE DOES THE JOB, WHO NEEDS THE FANCY PACKAGE! " "╔F THE SOFTWARE DOES NOT DO THE JOB, THEN SIMPLY DO NOT USE IT "AND PAY NOTHING; PASS IT ON TO SOMEONE ELSE, MAYBE THEY WILL FIND "IT USEFUL. ┴T LEAST IT DIDN'T COST YOU ANYTHING TO EXPERIMENT. " "╧N THE OTHER HAND, IF YOU FIND YOURSELF STILL USING THE PROGRAM "AFTER A COUPLE OF WEEKS, THEN OBVIOUSLY IT IS OF SOME WORTH TO "YOU AND YOU SHOULD SEND IN A CONTRIBUTION REFLECTING THAT WORTH. " " * ┴╥├ IS DISTRIBUTED AS ╞╥┼┼╫┴╥┼. " " * ┴╥├ IS NOT ╞╥┼┼ SOFT╫┴╥┼. " "╔F YOU USE ┴╥├ REGULARLY, THEN YOU SHOULD SEND IN A CONTRIBUTION. "╔F ALL YOU CAN AFFORD IS A COUPLE OF BUCKS, THEN SEND IN A COUPLE "OF BUCKS...ITS BETTER THAN NOTHING AT ALL. ╔F YOU HAVN'T SENT IN "A CONTRIBUTION, THEN YOU SHOULD NOT BE USING ┴╥├. " "┴╥├ IS PROTECTED BY COPYRIGHT. ╘HIS MEANS THAT THE ORIGINAL "COPYRIGHT HOLDER (┴MPERE ═ETAL AND/OR ├HRIS ╙MEETS) IS THE ONLY "PERSON THAT MAY LEGALLY DUPLICATE ┴╥├ OR PERMIT SOMEONE ELSE TO "DO SO. ┴MPERE ═ETAL DOES HOWEVER, PARTIALLY WAIVE ITS RIGHTS AS "COPYRIGHT HOLDER AS OUTLINED FOLLOWING: " " "┘╧╒ ═┴┘ ╬╧╘: " " 1) ─UPLICATE THE ╨╥╔╬╘┼─ DOCUMENTATION FOR ┴╥├ EITHER IN " WHOLE OR IN PART BY ANY MEANS FOR ANY PURPOSE. " " 2) ├HARGE ANY FEE WHATSOEVER FOR DUPLICATING THE MACHINE- " READABLE VERSION OF ┴╥├, WHETHER DONE FOR PROFIT OR " OTHERWISE. " " 3) ═ODIFY ┴╥├ OR ITS DOCUMENTATION IN ANY WAY. " " "┘╧╒ ═┴┘: " " 1) ╒SE ┴╥├ ON A TRIAL BASIS ONLY. ╔F YOU INTEND TO USE " ┴╥├ FOR MORE THAN JUST A TRIAL, THEN YOU MUST SEND IN " A CONTRIBUTION. " " 2) ─UPLICATE THE MACHINE READABLE FILES ASSOCIATED WITH " ┴╥├, PROVIDED THAT THIS IS DONE FREE OF CHARGE AND " WITHOUT MODIFICATION. " " "╞REEWARE "╘HERE ARE MANY WAYS IN WHICH ┴╥├ CAN BE IMPROVED. ╓ERSION 1.00 "USED ONLY STRAIGHT STORAGE AND ╚UFFMAN SQUEEZING. ╥UN-LENGTH "ENCODING WAS ADDED IN VERSION 1.30. ╓ERSION 2.00 ADDED "╠EMPEL-┌EV COMPRESSION AND IMPROVED ╚UFFMAN-SQUEEZING BY "COMBINING IT WITH RUN-LENGTH CODING. ╓ERSION 2.00 ARCHIVES CAN "ALSO BE CREATED IN A SINGLE PASS FOR INCREASED SPEED AT THE "EXPENSE OF A SMALL AMOUNT OF DISK STORAGE. " "╞UTURE IMPROVEMENTS INCLUDE MAKING ┴╥├ ROUTINES AVAILABLE TO THE "┬┴╙╔├ PROGRAMMER, MAKING ┴╥├ WORK ON VARIOUS DIFFERENT ├OMMODORE "COMPUTERS, FAST SERIAL ROUTINES, RANDOM ACCESS ARCHIVES, THE "ABILITY TO EXECUTE ARCHIVED PROGRAMS, IMPROVING COMPRESSOR "PERFORMANCE, THE ABILITY TO EXTRACT ═╙-─╧╙ ARCHIVES AND ├╨/═ "SQUEEZED OR CRUNCHED FILES. ╘HE LIST GOES ON AND ON.... " "╨ROGRAM DEVELOPMENT TAKES TIME. ╠OTS OF IT. ╘HE MORE SUPPORT WE "GET FROM YOU IN THE FORM OF CONTRIBUTIONS AND CONSTRUCTIVE "CRITICISM, THE MORE MOTIVATED WE WILL BE TO SPEND OUR TIME ON "IMPROVING ┴╥├. ╘HE AMOUNT OF TIME AND EFFORT WE WILL BE PUTTING "INTO ┴╥├ WILL BE IN DIRECT PROPORTION TO THE AMOUNT OF USER "SUPPORT WE GET. " "├ONTRIBUTIONS SHOULD BE SENT TO: " " ┴MPERE ═ETAL " 80 ╚ALE ╥OAD - ╒NIT 4 " ┬RAMPTON, ╧╬ ╠6╫ 3═1 ├ANADA " "┴ MINIMUM CONTRIBUTION OF $10.00 GETS YOU PRINTED DOCUMENTATION. "┴ MINIMUM CONTRIBUTION OF $20.00 GETS YOU A CURRENT PROGRAM DISK "AS WELL. ╔F YOU CONTRIBUTE A MINIMUM OF $20.00, YOU WILL ALSO BE "ELIGIBLE TO PURCHASE UPDATES AT COST. (─OCUMENTATION AT "$0.06/PAGE + $2.50 FOR DISKETTE + $2.50 POSTAGE) " "╨LEASE BE SURE TO INCLUDE YOUR CORRECT ADDRESS AND POSTAL/ZIP "CODE. " " "─╔╙├╠┴╔═┼╥ " "┴MPERE ═ETAL MAKES NO WARRANTY, NEITHER EXPRESSED NOR IMPLIED, "INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF "MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE REGARDING "THESE MATERIALS AND MAKES ┴╥├ AVAILABLE SOLELY ON AN 'AS IS' "BASIS. " "╔N NO EVENT SHALL ┴MPERE ═ETAL BE BE LIABLE TO ANYONE FOR "SPECIAL, COLLATERAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES IN "CONNECTION WITH OR ARISING OUT OF PURCHASE OR USE OF ┴╥├. ╘HE "SOLE AND EXCLUSIVE LIABILITY OF ┴MPERE ═ETAL, REGARDLESS OF THE "FORM OF ACTION, SHALL NOT EXCEED THE PURCHASE PRICE OF THE "MATERIALS DESCRIBED HEREIN. " "╔F YOU DO NOT AGREE TO THESE TERMS, THEN DO NOT USE ┴╥├. " " " "╒PDATES "╒╨─┴╘┼╙ " "╘HE EASIEST WAY TO GET AN UPDATE IS SIMPLY TO DOWNLOAD IT BY "MODEM FROM OUR BULLETIN BOARD AT (416) 458-0039 IN ╘ORONTO "╧NTARIO ├ANADA. ╘HE BOARD IS A PUBLIC ACCESS ╞╔─╧ SYSTEM, AND "YOU WILL NEED A TERMINAL WITH ╪═╧─┼═, ═╧─┼═7, ╦┼╥═╔╘, ═╔╬╔╘┼╠, OR "╘┼╠╔╬╦ FILE TRANSFER PROTOCOL IN ORDER TO DOWNLOAD FROM THE "BOARD. ╘HE MOST RECENT VERSION OF ┴╥├ WILL ALWAYS BE POSTED "WHERE IT CAN BE EASILY FOUND. ╔N ADDITION YOU WILL FIND VARIOUS "RELATED DOCUMENTATION AND ADDITIONAL UTILITIES COMPLEMENTARY TO "┴╥├ AS THEY BECOME AVAILABLE. ╔F YOU HAVE ANY QUESTIONS, LEAVE "THE ╙┘╙╧╨ A MESSAGE AND WE WILL DO OUR BEST TO ANSWER THEM. " "╘HE BOARD IS CURRENTLY OPERATING AT 300, 1200 AND 2400 BAUD. " "╫E WILL ALSO TRY TO POST A CURRENT VERSION OF ┴╥├ ON ├╧═╨╒╙┼╥╓┼, "(╟╧ ├┬═╨╥╟ AND CHECK THE ╚╔╟╚ ╠┼╓┼╠ ╒╘╔╠╔╘┘ SECTION WITH KEYWORD "┴╥├). ┘OU CAN ALSO CHECK THE ├OMMODORE ╙╔╟S OF ─┼╠╨╚╔ AND ╟┼NIE "WHICH SHOULD ALSO HAVE CURRENT COPIES OF ┴╥├. ╔F YOU ARE "PATIENT, YOU CAN ALSO JUST WAIT UNTIL IT IS AVAILABLE ON A LOCAL "BULLETIN BOARD IN YOUR AREA. " "╫HEN UPDATING BY ONE OF THE ABOVE METHODS, SUFFICIENT "DOCUMENTATION WILL BE AVAILABLE SO THAT YOU CAN FIGURE OUT HOW "TO USE ┴╥├. ├OMPLETE DOCUMENTATION IS ONLY AVAILABLE IN PRINTED "FORM TO REGISTERED USERS. " "╔F YOU WISH TO POST ┴╥├ ON YOUR BULLETIN BOARD FOR PUBLIC ACCESS, "THEN WE WOULD PREFER THAT YOU MAKE ONLY THE MOST-RECENT VERSION "AVAILABLE AND DELETE PREVIOUS VERSIONS. ╫E WILL BE COMING OUT "WITH A NUMBER OF EXTERNAL UTILITIES FOR ┴╥├ AND WILL BE MAKING "THE ASSUMPTION THAT ANYONE USING THEM HAS A CURRENT COPY OF ┴╥├. " "╫HEN UPDATING ┴╥├, WE WILL TRY TO STICK TO THE FOLLOWING VERSION "NUMBERING SCHEME: ┴╥├ (VERSION╪).┘┌ (E.G. ┴╥├2.20) " "╔F '┌' CHANGES, THEN A MINOR CHANGE HAS BEEN MADE TO ┴╥├, AND IT "IS PROBABLY NOT WORTH THE EFFORT OF UPDATING. ╔F '┘' CHANGES, "THEN A USEFUL CHANGE HAS BEEN MADE AND IT IS PROBABLY WORTH THE "EFFORT TO GET AN UPDATE. ╔F '╪' CHANGES, THEN A ═┴╩╧╥ CHANGE HAS "BEEN MADE, AND YOU WILL HAVE TO UPDATE IF YOUR VERSION OF ┴╥├ HAS "A LOWER VALUE OF '╪'. '╪' IS THE NUMBER THAT YOU SEE IN THE "COLUMN MARKED '╓' WHEN YOU LIST AN ARCHIVE'S DIRECTORY. " "╞OR EXAMPLE, WHEN WE ADDED THE '/W' SWITCH TO ─╔╥, THE VERSION "CHANGED FROM 1.33 TO 1.34. ╫HEN WE ADDED '┴╥├/╞', THE VERSION "CHANGED FROM 2.00 TO 2.10. ╫HEN WE ADDED THREE NEW DATA "COMPRESSION TECHNIQUES, THE VERSION CHANGED FROM 1.34 TO 2.00. " "╬OTE THAT IF YOUR VERSION OF ┴╥├ HAS THE SAME VALUE OF '╪' AS THE "LATEST VERSION, YOU WILL BE ABLE TO EXTRACT FILES FROM ARCHIVES "CREATED BY THE NEWER VERSION. ╔F '╪' IS LOWER THAN THE MOST "RECENT ┴╥├, THEN YOU MAY COME ACROSS SOME ARCHIVES WHICH YOUR "VERSION OF ┴╥├ CAN'T HANDLE. " "╘HE ACTUAL ┴╥├ PROGRAM ITSELF WILL BE DISTRIBUTED AS '┴╥├╪┘┌.╚', "WHERE '╪┘┌' IS THE VERSION NUMBER, AND '╚' WILL INDICATE WHAT "┬UGS ╔N ┴╥├ "MACHINE THE PROGRAM RUNS ON. ┴T PRESENT, '╚' CAN BE '4' FOR A "STANDARD ├-64 AND '8' FOR A ├-64 EQUIPPED WITH AN 80-COLUMN "ADAPTOR (┬╔-80). ╚OPEFULLY '╚' WILL TAKE ON VALUES LIKE '4032', "'8096', OR '128' IN THE NOT-TOO-DISTANT FUTURE. " " "┬╒╟╙ ╔╬ ┴╥├ " "┴S WE BECOME AWARE OF THEM, WE WILL TRY TO REPAIR ANY BUGS WHICH "MANIFEST THEIR UGLY HEADS. ╘HERE ARE A FEW BUGS WHICH MANAGED TO "SLIP BY US. ╙OME OF THEM ARE HARMLESS, AND SOME ARE NOT. ╘HERE "ARE A FEW THAT YOU SHOULD BE AWARE OF: " " ┴╥├ 1.00 " "WOULD OCCASIONALLY MAKE AN ARCHIVE ENTRY ONE BLOCK LONGER THAN IT "SHOULD BE. ╘HIS EXTRA BLOCK WOULD CONFUSE ┴╥├ WHEN EXTRACTING "THE ARCHIVE. ╔F AN ARCHIVE CREATED BY ┴╥├ 1.00 VERIFIES 'OK', "THEN IT IS OKAY. " " ┴╥├ 1.XX ( XX NOT 00 ) " "THESE VERSIONS HAD A BUG IN THE PACK ROUTINE. ╔F A CHARACTER "REPEATED 'N' TIMES WITH 'N>255', THEN IT WOULD UNPACK AS 'N+1' "BYTES. ╘HIS WOULD USUALLY RESULT IN A CHECKSUM ERROR, BUT UNDER "THE RIGHT CIRCUMSTANCES IT WOULD NOT (IN PARTICULAR, IN PICTURE "FILES WITH A LOT OF EMPTY SPACE). ┴╥├S NUMBERED 2.20 OR HIGHER "ARE SMART ENOUGH TO DETECT THIS PROBLEM AND WILL UN-PACK SUCH AN "ARCHIVE PROPERLY. " "╘HERE WAS ALSO ANOTHER PROBLEM WITH THE UNPACK ROUTINES AND THE "CHECKSUM CALCULATION. ╘HE LAST BYTE OF THE FILE WOULD "OCCASIONALLY BE INCLUDED IN THE CHECKSUM MORE THAN ONCE! ╘HIS "PROBLEM WAS IN FACT HARMLESS, EXCEPT FOR THE FACT THAT IT FOOLED "IT INTO THINKING THAT THE PREVIOUS PROBLEM WAS ALSO HARMLESS. " "╘HE PACK ROUTINES HAVE BEEN COMPLETELY REWRITTEN IN ┴╥├S NUMBERED "2.00 OR HIGHER; THE CHECKSUM CALCULATION IS NOW MORE RIGOROUS AND "WILL DETECT ERRORS THAT WOULD HAVE GONE UN-NOTICED BY ┴╥├S 1.XX " " ┴╥├ 2.10 " "╔N ORDER TO OVERCOME THE PROBLEM OF ╪═╧─┼═ PADDING, WE MADE ┴╥├ "2.10 CHECK FOR AND IGNORE ANY PADDING AT THE END OF AN ARCHIVE. "╒NFORTUNATELY, IF THE LAST ENTRY IN AN ARCHIVE HAPPENS TO BE ONLY "ONE BLOCK LONG, THEN ┴╥├ 2.10 IS STUPID ENOUGH TO IGNORE IT AS "╪═╧─┼═ PADDING. ╘HIS HAS BEEN FIXED IN ┴╥├ 2.20. " "╫HILE WE'RE ON THE SUBJECT OF ╪═╧─┼═ PADDING, ┴╥├S 1.XX CAN NOT "HANDLE IT PROPERLY. ╘HE ARCHIVE WILL STILL EXTRACT OKAY, BUT ┴╥├ "MAY SPIT OUT SOME GARBAGE AT THE END WHEN IT ENCOUNTERS THE "╪═╧─┼═ PADDING AND THINKS IT IS ANOTHER ARCHIVE ENTRY. " "┬LESS US ┴╥├ USER FOR WE HAVE SINNED. ╔T HAS BEEN SIX MONTHS "SINCE WE FIRST RELEASED ┴╥├ 1.00. ╞OR THESE AND ANY OTHER BUGS "WE HAVE FAILED TO MENTION, WE ARE TRULY SORRY. " "╔NTRODUCTION "╔╬╘╥╧─╒├╘╔╧╬ " "┴╥├ WAS INSPIRED BY THE PROGRAM OF THE SAME NAME WHICH HAS BEEN "AVAILABLE TO ═╙-─╧╙ USERS FOR SOME TIME NOW. ╔T ALLOWS YOU TO "TAKE SEVERAL RELATED FILES AND BACK THEM UP INTO A SINGLE ARCHIVE "FILE. ╘HE ARCHIVE CAN LATER BE EXTRACTED TO OBTAIN EXACT "DUPLICATES OF THE FILES THAT WENT INTO IT. ╙INCE ┴╥├ "AUTOMATICALLY COMPRESSES THE FILES AS THEY ARE BEING ARCHIVED, "THE RESULTING ARCHIVE FILE TAKES UP LESS DISK STORAGE SPACE THAN "THE ORIGINAL FILES. ╙AVINGS VARY WITH THE TYPES OF FILES BEING "ARCHIVED, AND IS TYPICALLY 50% FOR TEXT AND 10-30% FOR PROGRAM "FILES. " "╘HE PRIMARY ADVANTAGE OF ┴╥├ IS AS A BACKUP TOOL. ╫ORD "PROCESSING FILES, ASSEMBLER SOURCE CODE, DATABASE FILES, GRAPHICS "AND MUSIC FILES COMPRESS RATHER WELL. ╔N FACT, DUE TO THEIR "HEAVY USE OF GRAPHICS PICTURES, EVEN GAMES CAN SQUEEZE DOWN QUIT "WELL IN SOME INSTANCES. ╬ORMALLY, A 1541/4040 DISKETTE HAS A "CAPACITY OF 664 BLOCKS OF STORAGE. ╒SING ┴╥├, YOU CAN INCREASE "THIS TO THE EQUIVALENT OF ABOUT 800 BLOCKS FOR PROGRAM DISKS AND "1300 OR MORE FOR TEXT AND GRAPHICS DISKS. " "┴NOTHER BIG ADVANTAGE OF ┴╥├ IS THE FACT THAT SEVERAL FILES CAN "BE COMBINED INTO A SINGLE ARCHIVE. ╘HIS MAKES IT SIGNIFICANTLY "EASIER (AND FASTER) TO TRANSFER INFORMATION FROM ONE COMPUTER TO "ANOTHER VIA THE TELEPHONE LINES. ╔F THE BULLETIN BOARD YOU ARE "CALLING USES ┴╥├ FILES, YOU WILL SPEND LESS TIME READING "DIRECTORIES AND TRYING TO FIGURE OUT WHICH, AND HOW MANY FILES "YOU HAVE TO DOWNLOAD TO GET THE PROGRAM YOU WANT TO WORK! ╬OT "ONLY THIS, BUT AFTER YOU EXTRACT THE ARCHIVE, ALL OF THE FILES "WILL HAVE THE CORRECT NAME AND FILETYPE SO RENAMING FILES IS NOT "NESSESSARY. " "┴╥├ IS ALSO A USEFUL TOOL FOR GENERAL FILE MAINTENANCE. ═OVING "FILES BETWEEN DRIVES, RENAMING FILES, VIEWING DIRECTORIES, AND "THE EDITING OF SIMPLE TEXT FILES IS RATHER SIMPLE WITH ┴╥├. " "╫HEN ╚UFFMAN CODING IS USED TO SQUEEZE FILES, THE COMPRESSION "RATIO (THE ORIGINAL LENGTH DIVIDED BY THE SQUEEZED LENGTH) IS "ABOUT 1.11 FOR PROGRAMS, 1.6 FOR TEXT FILES, AND CAN BE 2.0 OR "MORE FOR GRAPHICS SCREENS. ╚UFFMAN CODED FILES SHOW UP AS "'SQUEEZED' ON AN ARCHIVE DIRECTORY. ╥UN-LENGTH SQUEEZING "(PACKING) IS SOMETIMES MORE EFFECTIVE, PARTICULARLY ON GRAPHICAL "INFORMATION. " "╓ERSION 2.00 OF ┴╥├ INTRODUCED THREE NEW DATA COMPRESSION "METHODS. '╙QUASHING' COMBINES RUN-LENGTH CODING WITH ╚UFFMAN "SQUEEZING AND IS GENERALLY SUPERIOR TO ╚UFFMAN SQUEEZING ALONE. "'├RUNCHING' IS BY FAR THE MOST INTERESTING METHOD USED TO DATE IN "THAT ┴╥├ WILL CHOOSE CRUNCHING AS THE MOST EFFICIENT COMPRESSOR "AS OFTEN AS 80 TO 90% OF THE TIME. ├RUNCHED FILES ARE STORED "USING THE ╠EMPEL-┌EV-╫ELCH ALGORITHM AND CAN RESULT IN VERY "IMPRESSIVE COMPRESSION RATIOS. ┴ TYPICAL TEXT FILE WILL COMPRESS "TO ABOUT 45% OF ITS ORIGINAL LENGTH, AND ╫ORD╨RO (TM) OR "╨APER├LIP (TM) FILES WILL CRUNCH DOWN TO ABOUT ONE THIRD OF THEIR "ORIGINAL LENGTH. " "─RIVE ╠ETTERS "├RUNCHING COMBINES RUN-LENGTH AND ╠EMPEL-┌EV-╫ELCH COMPRESSION "AND IS UNIQUE IN THAT IT CAN BE PERFORMED WITHOUT REQUIRING AN "INITIAL PASS THROUGH THE DATA FILE. ╔T IS NOW POSSIBLE TO "OVERRIDE ┴╥├'S CHOICE OF THE COMPRESSOR, AND CRUNCH EVERYTHING IN "ONLY ONE PASS! ┴LTHOUGH THIS DOES NOT NECESSARILY ENSURE THE "MOST EFFICIENT USE OF DISK SPACE, SIGNIFICANT TIME SAVINGS CAN BE "ACHIEVED WITH ONLY A SMALL SACRIFICE IN STORAGE. " "╔N GENERAL, ┴╥├ MAKES TWO PASSES THROUGH EACH SOURCE FILE. ╧N "THE FIRST PASS, ┴╥├ COUNTS THE NUMBER OF BYTES IN THE FILE AND "CALCULATES A 2-BYTE CHECKSUM FOR EACH FILE BEING ARCHIVED. ╘HE "CHECKSUM IS STORED IN THE ARCHIVE AND IS LATER USED TO VERIFY THE "FILE'S INTEGRITY. ┴╥├ ALSO PREPARES A FREQUENCY DISTRIBUTION OF "THE BYTES USED IN THE FILE AND USES IT TO GENERATE THE ╚UFFMAN "CODES. ╔T THEN CALCULATES WHAT THE RESULTANT LENGTH WOULD BE "USING EACH OF THE THREE STORAGE METHODS (STORE, SQUEEZE, SQUASH, "CRUNCH, OR PACK). ╨ASS TWO THEN WRITES THE FILE TO THE ARCHIVE "USING THE MOST EFFICIENT OF THE FIVE METHODS AVAILABLE. " "╔N ORDER TO ACHIEVE SOME OF THE FLEXIBILITY AND EASE OF USE OF "THE ═╙-─╧╙ VERSION, WE HAD TO DO SOMETHING ABOUT ├OMMODORE ─╧╙. "┴FTER ALL, ISN'T: " " DEL A:SCRAPFILE1 C:SCRAPFILE2 <RETURN> " "A HECK OF A LOT EASIER THAN: " " OPEN 15,8,15 " PRINT#15,''S0:SCRAPFILE1'' " CLOSE 15 " OPEN 15,9,15 " PRINT#15,''S0:SCRAPFILE2'' " CLOSE 15 " "OR WHAT ABOUT: " " MOVE A:ARC.EXE B:ARC.ASM C:USQ F: " "╘HAT WOULD TAKE SOME DOING! ┴ND YET IT'S THE TYPE OF THING YOU "WANT TO DO QUITE EASILY WHEN MANIPULATING YOUR DISK LIBRARY. " "╔N GENERAL, DRIVE LETTERS ARE BOTH EASIER AND MORE PRECISE THAN "DRIVE NUMBERS. ╔F YOU ARE FAMILIAR WITH ═╙-─╧╙ OR ├╨/═, YOU "PROBABLY PREFER DRIVE LETTERS. ╔F NOT, THEY MAY TAKE SOME "GETTING USED TO. ╫HAT WE'VE DONE IS ASSIGN EACH DRIVE A LETTER "ACCORDING TO THE TABLE BELOW: " " DRIVE LETTER DEVICE NUMBER,DRIVE " ------------ ------------------- " A 8 0 " B 8 1 " C 9 0 " D 9 1 " E 10 0 " F 10 1 " G 11 0 " H 11 1 "─RIVE ╠ETTERS "╘HUS, IF YOU WANT A PROGRAM ON DRIVE 1 OF UNIT 10, YOU CAN DO ANY "ONE OF THE FOLLOWING: " " DLOAD ''PROGRAM'',D1 ON U10 (BASIC 4.0) " LOAD ''1:PROGRAM'',10 (BASIC 2.0) " OR " LOAD ''F:PROGRAM'' (WITH ┴╥├) " "╔F YOU WANT TO LOAD ┴╬─ ╥╒╬ THE PROGRAM, JUST TYPE: " " F:PROGRAM <RETURN> " "┴╥├ WILL THEN LOAD AND RUN IT (OR '╙┘╙' TO IT, IF IT IS MACHINE "LANGUAGE). " "╔N ANY CASE, WE FELT THAT DRIVE LETTERS WERE SUFFICIENTLY USEFUL "THAT GETTING USED TO THEM WOULD BE WORTH THE BOTHER. ╔F YOU'RE "STILL NOT CONVINCED, THINK ABOUT THIS EXAMPLE AS YOU READ ON: " " ARC/C D:ARCFILE A:ASM.?? B:ED.?? C:* " "╫E THINK THAT YOU WILL GROW TO APPRECIATE THE ENVIRONMENT IN "WHICH ┴╥├ IS AVAILABLE. ╘HE COMMANDS THAT YOU REQUIRE MOST OFTEN "TO VIEW DIRECTORIES, MOVE FILES ABOUT, DELETE FILES, RENAME "FILES, OR EDIT SIMPLE TEXT FILES, ARE AT YOUR DISPOSAL. ╞UTURE "VERSIONS OF ┴╥├ WILL HAVE EVEN MORE COMMANDS. ╫E FELT THAT THIS "IS THE ENVIRONMENT IN WHICH ┴╥├ WOULD PROVE MOST USEFUL. " " "┴NYWAY, WITHOUT MUCH FURTHER ADO, WE'LL GIVE YOU A RUNDOWN OF THE "COMMANDS AVAILABLE..... " " [SQUARE BRACKETS] INDICATE OPTIONAL PARAMETERS " " <ANGLE BRACKETS> INDICATE REQUIRED PARAMETERS " " D: IS A DRIVE LETTER " (USUALLY A DESTINATION DRIVE) " " S: IS A DRIVE LETTER " (USUALLY A SOURCE DRIVE) " " " " " " " " " " " " " " " " "╟ENERAL ─╧╙ ├OMMANDS "1) ╟┼╬┼╥┴╠ ─╧╙ ├╧══┴╬─╙: "========================= " "A: "----------------------------------------------------------------- "╙ELECTS DRIVE 'A' (UNIT 8, DRIVE 0) AS THE DEFAULT DRIVE. "╫HENEVER A COMMAND USES A DRIVE LETTER AS AN OPTIONAL PARAMETER, "AND YOU DO NOT SPECIFY THE DRIVE LETTER, THE DEFAULT DRIVE WILL "BE USED. ╓ALID DRIVES ARE THE LETTERS 'A' THROUGH 'H'. " " "D:FILENAME "----------------------------------------------------------------- "╘HIS WILL SEARCH DRIVE 'D' (UNIT 9, DRIVE 1) FOR THE PROGRAM "SPECIFIED AND IF IT IS FOUND IT WILL BE RUN. ╔F IT IS A MACHINE "LANGUAGE PROGRAM, THEN ┴╥├ WILL '╙┘╙' TO ITS LOAD ADDRESS. ╬OTE "THAT THE ╠╧┴─ IS NON-RELOCATING (THE SAME AS ╠╧┴─ WITH ',8,1'). " " "DATE DD,MM,YYYY "----------------------------------------------------------------- "╘HIS IS USED TO SET THE DATE. 'DD' IS THE DAY, 'MM' IS THE "MONTH, AND 'YYYY' IS THE YEAR. ╙INCE THE DATE IS STORED "INTERNALLY IN THE SAME FORMAT AS USED ON THE ╔┬═ ╨├, THE POSSIBLE "VALUES FOR 'YYYY' ARE 1980 THROUGH 1980+127. " "╔F YOU ENTER AN ILLEGAL VALUE FOR ONE OF THE ABOVE PARAMETERS, "THEN THE DATE WILL NOT CHANGE. " "╘HE DATE IS STORED IN THE HEADER OF EVERY ARCHIVE ENTRY, AND IS A "USEFUL WAY TO KEEP TRACK OF WHICH BACKUP IS MORE RECENT THAN "ANOTHER. ╔T IS ALSO USEFUL WHEN POSTING PROGRAMS ON BULLETIN "BOARDS FOR PUBLIC ACCESS, AS IT INDICATES HOW RECENT A PARTICULAR "VERSION OF A PROGRAM IS. ╧F COURSE, THE DATE WON'T ALWAYS BE "MEANINGFUL. ╔N THIS CASE WE SUGGEST YOU JUST LEAVE IT SET TO THE "DEFAULT OF '01JAN1980'. " " "DIR[/W] [S:[PATTERN1]] [S:[PATTERN2]] ... "----------------------------------------------------------------- "╠ISTS A DIRECTORY TO THE SCREEN. ╙OME EXAMPLES ARE: " " DIR - LISTS DEFAULT DIRECTORY " " DIR A: - LIST DIRECTORY OF DRIVE 'A:' " " DIR B:??? - LIST FILES ON DRIVE 'B:' WHOSE " NAMES ARE 3 CHARACTERS IN " LENGTH " " DIR A*,B* - LIST FILES FROM THE DEFAULT " DRIVE WHOSE NAMES START WITH " 'A' OR 'B' " " DIR A:T* C:T* - LISTS ALL FILES ON DRIVES 'A:' " ┴╬─ 'C:' WHOSE NAMES BEGIN " WITH 'T' "╟ENERAL ─╧╙ ├OMMANDS " DIR/W - LISTS THE DEFAULT DIRECTORY, " FILENAMES ONLY " " DIR/W A:J* B:K* - LISTS FILENAMES ONLY FOR FILES ON " DRIVE 'A:' WHOSE NAMES BEGIN WITH " 'J' ┴╬─ FILES ON DRIVE 'B:'WHOSE " NAMES BEGIN WITH 'K' " " "DEL [D:]<PATTERN> [[D:PATTERN] [D:PATTERN]....] "----------------------------------------------------------------- "╙CRATCHES FILES FROM THE SPECIFIED DRIVES. ╒P TO 9 DIFFERENT "PATTERNS MAY BE GIVEN, BUT ONLY ONE IS REQUIRED. ╙OME EXAMPLES "ARE: " " DEL ARC - DELETE 'ARC' FROM DEFAULT DRIVE " " DEL A:TEMP* B:TEMP* - DELETE ALL FILES FROM DRIVE 'A:' " OR DRIVE 'B:' WHOSE NAMES START " WITH 'TEMP' " " "MOVE <[S:]PATTERN> [[[S:]PATTERN]...] <D:> "----------------------------------------------------------------- "├OPIES FILES BETWEEN DRIVES. ┴S MANY AS EIGHT PATTERNS MAY BE "GIVEN AS PARAMETERS. ╔F EITHER THE SOURCE OR THE DESTINATION "DRIVE IS OMITTED, IT IS ASSUMED TO BE THE DEFAULT DRIVE. ╙OME "EXAMPLES ARE: " " MOVE A:ARC C: - MOVE FILE 'ARC' ON DRIVE 8,0 " TO DRIVE 9,0 " " MOVE A:* B:* C: - MOVE ALL FILES FROM DRIVES 'A:' " ┴╬─ 'B:' TO DRIVE 'C:' " " MOVE B:TEST - MOVES FILE 'TEST' ON DRIVE 'B:' " TO THE DEFAULT DRIVE " " MOVE TEST B: - MOVES FILE 'TEST' ON THE " DEFAULT DRIVE TO DRIVE 'B:' " "╬╧╘┼: ═╧╓┼ WON'T HANDLE RELATIVE FILES PROPERLY....YET. ┴LSO, " YOU CANNOT RENAME A FILE AS YOU MOVE IT. ┘OU MUST FIRST " MOVE IT TO THE DESTINATION DRIVE AND THEN RENAME IT ONCE " IT IS THERE " "REN [D:]OLDNAME NEWNAME "----------------------------------------------------------------- "╥ENAMES A FILE NAMED 'OLDNAME' TO 'NEWNAME' ON DRIVE 'D:'. " " "TYPE [S:]<PATTERN> "----------------------------------------------------------------- "╙IMPLY COPIES THE CONTENTS OF THE FILE NAMED TO THE SCREEN. ╧NLY "THE FIRST FILE FOUND WILL BE DISPLAYED IF WILDCARDS ARE USED. " " "┼DITOR ├OMMANDS "> (─╔╙╦ ├╧══┴╬─╙) "----------------------------------------------------------------- "╘HIS SHOULD BE A FAMILIAR COMMAND. ╔T IS THE UNIVERSAL WEDGE, "─╧╙ 5.1, ─╧╙ WEDGE, OR WHATEVER YOU WANT TO CALL IT. ╘HE ONLY "DIFFERENCE IS THAT THE COMMAND ALWAYS GOES TO THE DEFAULT DEVICE. "┴SSUMING THAT 'A:' IS THE DEFAULT DRIVE, SOME EXAMPLES ARE: " " >I1 - INITIALIZE DRIVE 1 (B:) " " >C0=1 - COPY DRIVE 1 TO DRIVE 0 ON " UNIT 8 (DUAL DRIVE) " " >R1:TEST=TEXT - RENAMES 'TEXT' TO 'TEST' " ON DRIVE 'B: " " >$0 - LISTS DIRECTORY OF DRIVE 'A:' " " >$C: - LISTS DIRECTORY OF DRIVE 'C:' " " "SIZE [S:]<FILENAME> "----------------------------------------------------------------- "├OUNTS AND DISPLAYS THE NUMBER OF BYTES IN A FILE. ╔F THE FILE "IS A PROGRAM, YOU MAY WANT TO DEDUCT TWO BYTES FROM THE LENGTH "SINCE THE LOAD ADDRESS IS INCLUDED IN THE COUNT. " " "START [S:]<FILENAME> "----------------------------------------------------------------- "╨RINTS THE LOAD ADDRESS OF A PROGRAM FILE. " " "2) ┼─╔╘╧╥ ├╧══┴╬─╙: "==================== " "╘HE EDITOR IS PRIMARILY INTENDED TO EDIT TEXT FILES. ╔T WAS "DESIGNED TO BE A TEXT EDITOR FOR USE IN EDITING ASSEMBLY LANGUAGE "SOURCE FILES, ALTHOUGH IT COULD BE USED TO EDIT ┬┴╙╔├ PROGRAMS AS "WELL. 'FIND', 'CHANGE', AND 'RENUM', HOWEVER, WILL NOT RECOGNIZE "┬┴╙╔├ TOKENS OR LINE NUMBER REFERENCES, SO YOU WOULD BE BETTER "OFF USING '╨╧╫┼╥' (TM) OR '╙┘╙╥┼╙' (TM) OR SOME OTHER EDITOR FOR "┬┴╙╔├ PROGRAMS. " " "TEXT "----------------------------------------------------------------- "╘HIS COMMAND PUTS THE EDITOR IN TEXT MODE. ┴NY UPPER-CASE "CHARACTERS NOT IN QUOTES WILL BE FORCED TO LOWER CASE, AND ┬ASIC "KEYWORDS WILL NOT BE TOKENIZED. ╫HEN LISTING A ┬ASIC PROGRAM, "YOU SHOULD SET ┬┴╙╔├ MODE, BECAUSE IN TEXT MODE, ┬┴╙╔├ TOKENS ARE "NOT EXPANDED. " " "BASIC "----------------------------------------------------------------- "╨UTS THE EDITOR IN ┬┴╙╔├ MODE. ╠OWER CASE IS NOT FORCED, AND "BASIC KEYWORDS WILL BE TOKENIZED AND EXPANDED BY ╠╔╙╘. "┼DITOR ├OMMANDS "AUTO [INCREMENT] "----------------------------------------------------------------- "╘URNS ON AUTOMATIC LINE NUMBERING. ┴UTO WITH NO INCREMENT "DISABLES AUTO. " " "COLD "----------------------------------------------------------------- "╙AME AS '╙┘╙64738' ON THE 64 (├╧╠─ ╙╘┴╥╘). ╔F YOU HAVE A RESET "BUTTON ON YOUR 64, OR IF YOU ARE USING A ├-128, THEN YOU CAN "RE-ENABLE ┴╥├ BY TYPING '╙┘╙ 12*4096' AFTER A RESET. " " "CHANGE/SEARCH STRING/REPLACE STRING/, RANGE "----------------------------------------------------------------- "├HANGES THE SEARCH STRING TO THE REPLACE STRING. '/' CAN BE "ANYTHING THAT IS NOT INCLUDED IN 'SEARCH STRING' OR 'REPLACE "STRING'. 'RANGE' IS A RANGE OF LINE NUMBERS USING THE SAME "SYNTAX AS THE ┬ASIC '╠╔╙╘' ├OMMAND. ╞OR EXAMPLE: " " CHANGE/$FFD2/CHROUT/,2000- CHANGES ALL OCCURENCES OF " '$FFD2' TO 'CHROUT' IN LINES " NUMBERED 2000 AND HIGHER " " "DELETE RANGE "----------------------------------------------------------------- "─ELETES A RANGE OF LINES FROM MEMORY USING THE SAME SYNTAX AS THE "┬ASIC 'LIST' COMMAND: " " DELETE -2000 DELETES LINES UP TO AND " INCLUDING LINE 2000 " " DELETE 3010-4030 DELETE LINES 3010 TO 4030 " INCLUSIVE " " "FIND/STRING/, RANGE "----------------------------------------------------------------- "╨RINTS (DISPLAYS) LINES THAT CONTAIN 'STRING'. " " "GET[/CHAR] [D:]FILENAME [,STARTLINE] "----------------------------------------------------------------- "╙IMILAR TO LOAD, EXCEPT THE FILE IS A SEQUENTIAL TEXT FILE. ╔F "'STARTLINE' IS GIVEN, THEN THE FILE IS APPENDED, WIPING OUT ANY "LINES NUMBERED EQUAL TO 'STARTLINE' OR HIGHER. " "╙INCE BLANK LINES AND UPPER-CASE ALPHABETICS TEND TO DISRUPT THE "SCROLLING OF TEXT, THE '╙╠┴╙╚ ╤╒╧╘┼╙' SWITCH: " " /'' (╥┼═┼═┬┼╥: TWO '' HERE MEANS ╧╬┼ ─╧╒┬╠┼-╤╒╧╘┼╙) " "(A ╙╠┴╙╚ FOLLOWED BY THE ─╧╒┬╠┼-╤╒╧╘┼╙ CHARACTER) IS INCLUDED TO "ALLOW INCLUSION OF A QUOTATION MARK (OR ANY OTHER CHARACTER) AT "THE BEGINNING OF EACH LINE. ╘HIS ALLOWS YOU TO MANIPULATE THESE "TYPES OF FILES IN ╥┴═. "┼DITOR ├OMMANDS "KILL "----------------------------------------------------------------- "─ISABLES THE EDITOR, SCROLL, AND RESTORES STANDARD LOAD/SAVE AND "OTHER VECTORS. " " "RENUM <FROM,START,INCREMENT> "----------------------------------------------------------------- "╥ENUMBERS LINES STARTING WITH LINE 'FROM'. ┴NY LINES NUMBERED "LOWER THAN 'FROM' ARE NOT AFFECTED. ╘HIS COMMAND SHOULD NOT BE "USED ON ┬┴╙╔├ PROGRAMS, AS IT DOES NOT ATTEMPT TO UPDATE ANY ╟╧╘╧ "OR ╟╧╙╒┬ REFERENCES ACCORDINGLY. " " "PUT <[D:]FILENAME> [,RANGE] "----------------------------------------------------------------- "╙TORES TEXT FROM MEMORY TO DISK. ╔F THE FILE EXISTS, IT WILL BE "BE DELETED BEFORE THE NEW COPY IS TRANSFERRED TO DISK. " " "REPEAT "----------------------------------------------------------------- "┼NABLES PROGRAM SCROLL AND REPEAT ON ALL KEYS. " " "OFF "----------------------------------------------------------------- "╦ILLS REPEAT AND PROGRAM SCROLL. " " "OLD "----------------------------------------------------------------- "╥ECOVERS FROM ╬┼╫. " " "HEX (NUMBER) "----------------------------------------------------------------- "├ONVERTS A DECIMAL NUMBER TO A HEXADECIMAL NUMBER. " " "HEX ($HEXNUMBER) "----------------------------------------------------------------- "├ONVERTS A HEXADECIMAL NUMBER TO A DECIMAL NUMBER. " " "# "----------------------------------------------------------------- "╙HORTHAND FOR: RENUM 1,1000,10 " " " " " " " " " "├REATING - ┴PPENDING "3) ┴╥├: "======== " "* ├╥┼┴╘╔╬╟ ┴╬ ┴╥├╚╔╓┼: " "ARC/C <[D:]ARCFILE[.ARC]> <[S:]PATTERN> [[S:]PATTERN]] "ARC/CX <[D:]ARCFILE[.ARC]> <[S:]PATTERN> [[S:]PATTERN]] "----------------------------------------------------------------- "├REATES AN ARCHIVE ON DRIVE 'D:' NAMED 'ARCFILE.ARC'. ┴S MANY AS "EIGHT PATTERNS MAY BE GIVEN. ╘HE POSSIBLE VALUES FOR 'X' ARE: " " N - NO COMPRESSION; STORE ONLY P - PACK ONLY " C - CRUNCH ONLY (TWO PASSES) Q - SQUASH ONLY " 1 - CRUNCH ONLY (ONE PASS) S - SQUEEZE ONLY " "╔F YOU CHOOSE OPTION 'X=1', THEN PART OF THE INFORMATION THAT ┴╥├ "NEEDS TO UN-ARCHIVE THE FILE MUST BE STORED AT THE END OF THE "ARCHIVE ENTRY RATHER THAN THE BEGINNING. ╔N PARTICULAR, THIS IS "THE FILE'S ORIGINAL LENGTH AND THE CHECKSUM. " "╒NFORTUNATELY, ┴╥├ NEEDS TO KNOW A RELATIVE FILE'S LENGTH WHEN IT "IS AT THE START OF THE ARCHIVE ENTRY SO THAT DISK SPACE CAN BE "PROPERLY ALLOCATED. ╘HEREFORE, ┴╥├ WILL NOT ALLOW THE SINGLE-PASS "CRUNCH OPTION FOR RELATIVE FILES. ╔F YOU DO SELECT 'X=1' WHEN "ARCHIVING A GROUP OF FILES, ANY RELATIVE FILES ENCOUNTERED WILL "BE PROCESSED AS IF YOU HAD CHOSEN 'X=C'. ╙OME EXAMPLES: " " ARC/C A:SQ B:SQ.* B:USQ.* " ╘HIS EXAMPLE CREATES AN ARCHIVE NAMED 'SQ.ARC' ON " DRIVE 'A:' WHICH INCLUDES ALL FILES FROM DRIVE 'B:' " WHOSE NAMES BEGIN WITH 'SQ.' OR 'USQ.' " " ARC/CS A:TEST.ARC F:* " ┴RCHIVES ALL FILES FROM DRIVE 10,1 TO 'TEST.ARC' " ON DRIVE 8,0 AND SQUEEZES ALL ENTRIES " " ARC/C SEQ B:*=S " ┴RCHIVES ALL SEQUENTIAL FILES ON DRIVE 'B:' TO " 'SEQ.ARC' ON THE DEFAULT DRIVE " "╨REVIOUS VERSIONS OF ┴╥├ WOULD ALLOW YOU TO ENCRYPT AN ARCHIVE BY "SPECIFYING A PASSWORD WHEN CREATING AN ARCHIVE. ╒NFORTUNATELY, "THIS CREATES A NUMBER OF PROBLEMS WHEN CRUNCHING FILES AND HAD TO "BE ELIMINATED. ┬ESIDES, WE NEVER USED IT ANYWAY. ─ID ANYONE? " " "* ┴╨╨┼╬─╔╬╟ ╘╧ ┴╬ ┼╪╔╙╘╔╬╟ ┴╥├╚╔╓┼: " "ARC/A[X] <[D:]ARCFILE[.ARC]> <[S:]PATTERN> [[S:]PATTERN]] "----------------------------------------------------------------- "╘HIS COMMAND IS ALMOST THE SAME AS THE 'CREATE' COMMAND, AND ALL "OF THE ABOVE EXAMPLES APPLY. ╘HE ONLY DIFFERENCE IS THAT THE "ARCHIVE FILE MUST EXIST, AND THE NEW ENTRIES ARE APPENDED TO IT. " "╔F THE ARCHIVE DOES NOT EXIST, A 'FILE NOT FOUND' MESSAGE IS "ISSUED AND THE PROGRAM ABORTS. " "┼XTRACTING "╙OMETIMES THE NUMBER OF BLOCKS DISPLAYED ON A DIRECTORY LISTING "DOES NOT AGREE WITH ┴╥├ AFTER AN APPEND. ╘HIS IS A BUG IN "├OMMODORE ─╧╙, AND SHOULD BE HARMLESS. ╧DDLY ENOUGH, IF YOU TRY "TO FIX THIS BY VALIDATING THE DISK, YOU WILL BE WASTING YOUR TIME "SINCE THE DIRECTORY BLOCK COUNT WILL NOT BE AFFECTED. " "╙INCE ┴╥├ CAN HANDLE ANY ARCHIVE CREATED BY LOWER VERSIONS OF "┴╥├, IT IS OKAY TO APPEND TO A VERSION 1 ARCHIVE. " "┘OU SHOULD EXERCISE SOME CAUTION WHEN APPENDING TO ARCHIVES. "┼VERY ARCHIVE MUST BE AN INTEGER MULTIPLE OF 254 BYTES IN LENGTH. "╫HEN TRANSFERRING ARCHIVES VIA MODEM USING THE ╪═╧─┼═ PROTOCOL, "FILES ARE TRANSFERRED IN 128-BYTE BLOCKS. ╔F THE FILE IS NOT AN "INTEGER MULTIPLE OF 128 BYTES IN LENGTH, AS THE MAJORITY OF FILES "ARE NOT, ╪═╧─┼═ 'PADS' THE FILE WITH BLANKS OR NULLS. "├ONSEQUENTLY, AN EXTRA DISK SECTOR GETS ADDED TO THE END OF AN "ARCHIVE! ╔T IS EASY TO FIX THIS PROBLEM BY USING A DISK DOCTOR "PROGRAM. ╙IMPLY CHANGE THE LINK FOR THE SECOND-LAST SECTOR IN "THE ARCHIVE TO (0,255). " "┘OU SHOULD HAVE NO PROBLEM EXTRACTING FILES FROM ╪═╧─┼═ "DOWNLOADED ARCHIVES, BECAUSE ┴╥├ WILL IGNORE THIS ╪═╧─┼═ PADDING. "┬┼╞╧╥┼ ┘╧╒ ┴╨╨┼╬─ TO AN ARCHIVE, YOU SHOULD FIX THIS PROBLEM. ╔F "YOU DON'T, THE FILES APPENDED TO THE ARCHIVE WILL NOT BE ABLE TO "BE DE-ARCHIVED. " "╫E HAVE ADDED A NEW COMMAND TO ┴╥├ TO CHECK AN ARCHIVE FOR THIS "TYPE OF PROBLEM. ╙IMPLY TYPE: " " ARC/F ARCHNAME[.ARC] " "┴╥├ WILL TRACE THE TRACK,SECTOR LINKS FOR THE ARCHIVE AND GET RID "OF THE LAST SECTOR IN THE ARCHIVE. ╔F THE ARCHIVE IS OKAY, AND "THE LINK FOR THE LAST SECTOR IS ALREADY (0,255) AS IT SHOULD BE, "THEN ┴╥├ DOES NOTHING AND PRINTS THE MESSAGE: " " ARCHIVE IS OK. " "╔F THE ARCHIVE IS BAD AND THE LINK IS ANYTHING OTHER THAN (0,255) "THEN ┴╥├ WILL GO TO THE SECOND-LAST SECTOR IN THE ARCHIVE AND "CHANGE ITS LINK TO (0,255). ╘HIS DROPS THE EXTRA SECTOR ADDED BY "THE ╪═╧─┼═ PADDING. ┴╥├ WON'T FREE UP THE DELETED SECTOR, NOR "WILL IT ADJUST THE DIRECTORY BLOCK COUNT FOR THE ARCHIVE. ╔F YOU "NEED THE EXTRA BLOCK FREE, THEN VALIDATE THE DISK TO GET IT BACK. " " "* ┼╪╘╥┴├╘╔╬╟ ╞╔╠┼╙ ╞╥╧═ ┴╬ ┴╥├╚╔╓┼: " "ARC/X[D] <[D:]ARCHFILE[.ARC]> [PATTERN1] [PATTERN2] ... "----------------------------------------------------------------- " "╘HIS COMMAND IS USED TO EXTRACT FILES FROM AN ARCHIVE. ╔F NO "PATTERNS ARE SPECIFIED, THEN ┴╥├ WILL EXTRACT ALL FILES FROM THE "ARCHIVE. ╫HEN PATTERNS ARE GIVEN, THEN ONLY THOSE FILES IN THE "ARCHIVE WHICH MATCH ONE OF THE PATTERNS WILL BE EXTRACTED. " " "╓IEWING "╙INCE ┴╥├ NO LONGER SUPPORTS ENCRYPTION OF DATA FILES, IT WON'T "BE ABLE TO HANDLE AN ENCRYPTED FILE. ┘OU WILL HAVE TO USE AN "EARLIER VERSION OF ┴╥├. ╘HE FILE WILL UN-ARCHIVE OKAY, BUT IT "WILL STILL BE ENCRYPTED. ╘HIS IS THE ONLY EXCEPTION TO THE RULE "THAT ┴╥├ WILL HANDLE ANY ARCHIVE CREATED BY ANY PREVIOUS VERSION "OF ┴╥├. ╞OR THE SAKE OF COMPLETENESS, HOWEVER, WE ARE WRITING A "LITTLE EXTERNAL UTILITY WHICH CAN BE USED TO UN-ENCRYPT THE FILE "ONCE DE-ARCHIVED AND WILL INCLUDE IT WITH LATER VERSIONS OF ┴╥├. "╙OME EXAMPLES (NOTING THAT 'ARC/X' AND 'ARC/E' AR SYNONYMS): " "ARC/X A:SQ ┼XTRACTS ALL FILES FROM 'SQ.ARC' ON DRIVE 8,0 " AND PUTS THEM ON THE DEFAULT DISK " "ARC/X A:SQ * ╙AME AS THE ABOVE " "ARC/XF B:TEMP.ARC ┼XTRACTS ALL FILES FROM 'TEMP.ARC' ON DRIVE " 'B:' (8,1) AND PUTS THEM ON THE DISK IN " DRIVE 'F:' (10,1) " "ARC/E C:BOOK030386 CHAPTER1 ┼XTRACTS ONLY THE FILE 'CHAPTER1' " FROM THE ARCHIVE 'BOOK030386' ON DRIVE 'C:' " " "* ╓╔┼╫╔╬╟ ┴╬ ┴╥├╚╔╓┼ ─╔╥┼├╘╧╥┘: " "ARC/L <[D:]ARCHNAME[.ARC]> "----------------------------------------------------------------- "╘HIS IS USED TO GET A LISTING OF THE FILES IN AN ARCHIVE. ┴ "TYPICAL ARCHIVE DIRECTORY MIGHT LOOK LIKE THE FOLLOWING: " " ARC/L A:ARCHELP " FILE ARCHIVE UTILITY VERSION 2.20 " 08/86 ... CHRIS SMEETS " DIRECTORY FOR ARCHIVE: A:ARCHELP.ARC " ====================================================== " FILENAME TYPE BLKS NOW V STOWAGE DATE " ====================================================== " XARC.TYPEME P 129 41 2 CRUNCHED 24AUG86 " SAMPLES S 22 9 2 CRUNCHED 24AUG86 " ================ ==== ==== " 2 FILES 151 50 " "╘HE FIRST TWO COLUMNS GIVE THE FILENAME AND ITS TYPE (P,S,U OR "R). ╘HE NEXT TWO COLUMNS GIVE THE FILE'S LENGTH IN DISK BLOCKS "BEFORE AND AFTER COMPRESSION. ╔F THE FILE WAS RELATIVE, THEN YOU "MAY NOT SEE THE SAME NUMBER AS YOU WOULD ON THE DIRECTORY, SINCE "THE RELATIVE FILE'S SIDE SECTORS ARE NOT NEEDED BY ┴╥├. " "╘HE COLUMN LABELED 'V' IS THE VERSION NUMBER OF THE ARCHIVE. ┴T "PRESENT THERE ARE THREE POSSIBLE VERSIONS: '1' REFERS TO "ARCHIVES CREATED BY ┴╥├ PROGRAMS NUMBERED 1.XX AND '2' STANDS FOR "ARCHIVES CREATED BY ┴╥├ VERSION 2.XX. ╔N ADDITION, IF YOU ARE "LOOKING AT AN ═╙-─╧╙ ARCHIVE, THE VERSION WILL BE '╔' (*). " ---------------------- "* ('┴╥├/╠' SHOULD HANDLE ANY ═╙-─╧╙ ARCHIVE CREATED BY ┴╥├S "NUMBER 5.10 OR LOWER. ╨RESENTLY, THIS IS THE ONLY ┴╥├ FUNCTION "THAT SUPPORTS ═╙-─╧╙ ARCHIVES.) "╨RINTING - ╓ERIFYING "╘HE NEXT COLUMN GIVES THE COMPRESSION METHOD THAT WAS USED TO ┴╥├ "THE FILE, AND THE LAST COLUMN IS ONLY DISPLAYED IF YOU ARE USING "THE 80-COLUMN VERSION OF ┴╥├. " " "* ╘┴╦╔╬╟ ┴ ╠╧╧╦ ┴╘ ╫╚┴╘'╙ ╔╬ ┴╬ ┴╥├╚╔╓┼: " "ARC/PX/Y <[D:]ARCHNAME[.ARC]> [[PATTERN1] [PATTERN2]...] "----------------------------------------------------------------- "╘HIS IS USED TO PRINT (DISPLAY) THE SPECIFIED FILES IN AN ARCHIVE "TO THE SCREEN. ╘HE SYNTAX IS SIMILAR TO THAT FOR '┴╥├/╪', EXCEPT "THAT THE OUTPUT IS TO SCREEN INSTEAD OF TO DISK. " "╘HE OPTIONAL SWITCHES 'X' AND 'Y' CAN TAKE THE FOLLOWING VALUES: " " X=P ├ONVERTS FROM STANDARD ┴╙├╔╔ TO NONSTANDARD " ├OMMODORE ASCII (╨┼╘SCII) " " X=A ├ONVERTS FROM ╨┼╘SCII TO TRUE ┴╙├╔╔ " " Y=P ╙ENDS OUTPUT TO THE PRINTER RATHER THAN TO THE SCREEN. " "╬╧╘┼: ┬┼╞╧╥┼ ╥╒╬╬╔╬╟ ┴╥├, YOU MUST SET THE PRINTER'S DEVICE " NUMBER AND SECONDARY ADDRESS AS FOLLOWS: " " ╨╧╦┼ 2051,(DEVICE NUMBER) " ╨╧╦┼ 2052,(SECONDARY ADDRESS) " " ╘HESE POKES MUST BE MADE ┬┼╞╧╥┼ YOU RUN ┴╥├. ╔F YOU DON'T " WANT TO DO THIS EVERY TIME YOU RUN ┴╥├, THEN RE-SAVE ┴╥├; " ┬┼╞╧╥┼ RUNNING IT! ╘HE DEFAULT VALUES ARE DEVICE=4, ╙┴=0. " " "ARC/V <[D:]ARCHNAME[.ARC]> [[PATTERN1] [PATTERN2]...] "----------------------------------------------------------------- "╘HIS IS USED TO VERIFY THE CONTENTS OF AN ARCHIVE. ┴╥├ "CALCULATES A 2-BYTE CHECKSUM FOR EACH FILE IN AN ARCHIVE. ╘HE "CHECKSUM IS CALCULATED USING THE BYTES OF THE ORIGINAL FILE "BEFORE THEY ARE PASSED ON TO THE COMPRESSION ROUTINES. " "╫HEN YOU VERIFY AN ARCHIVE, ┴╥├ ACTUALLY DE-COMPRESSES EACH "ARCHIVE ENTRY AND CALCULATES A NEW CHECKSUM USING THE BYTES "PASSED TO IT BY THE DECOMPRESSOR. ┬OTH CHECKSUMS SHOULD BE THE "SAME. ╔F THEY DO NOT MATCH, AN ERROR MESSAGE IS DISPLAYED WHICH "INDICATES THAT THE ARCHIVE ═┴┘ HAVE BEEN CORRUPTED DUE TO A DISK "ERROR OR A TRANSMISSION ERROR DURING UP/DOWNLOADING. " "┴GAIN, THE SYNTAX IS THE SAME AS THAT FOR ┴╥├/╪. " "┬Y NOW, YOU MAY HAVE NOTICED THAT '/╪', '/╨', AND '/╓' ARE ALL "MINOR VARIATIONS OF THE SAME THING. " " " " " " "═EMORY ═AP "4) ═┼═╧╥┘ ═┴╨: "=============== " " $033C-$03FF - CASSETTE BUFFER; USED BY ┴╥├ " $0801-$0FFF - NOT USED " $1000-$4FFF - WORK SPACE FOR ┴╥├/├ AND ┴╥├/╪; " ├╥╒╬├╚ STRING TABLE IS STORED HERE " $5000-$7FFF - WORKSPACE FOR ┴╥├ AND ═╧╓┼ " COMMANDS ONLY; ALL OTHER COMMANDS " LEAVE THIS AREA ALONE " $8000-$8FFF - USED IN 80-COLUMN VERSION (╥╧═) " $9000-$97FF - NOT USED " $9800-$9FFF - 80-COLUMN SCREEN; " ╬OT USED IN 40-COLUMN ┴╥├ " $A000-$BFFF - PROGRAM AREA; ┴╥├, ═╧╓┼, AND ─╔╥ " $C000-$CFFF - PROGRAM AREA; ┼DITOR COMMANDS " (SYS 12*4096 TO ENABLE ┴╥├ AFTER " A ╦╔╠╠) " $D000-$FFFF - WORK SPACE FOR ┴╥├/├ AND ┴╥├/╪ " "┘OU MAY NOTICE THAT THERE IS A RATHER SIGNIFICANT JUMP IN THE "AMOUNT OF WORKSPACE THAT ┴╥├ NEEDS TO DO ITS JOB FROM PREVIOUS "VERSIONS OF ┴╥├ (28╦ TO BE EXACT). ╘HIS IS DUE TO THE ├╥╒╬├╚ "ROUTINES, WHICH ARE RATHER DEMANDING IN TERMS OF MEMORY. ╔F YOU "HAVE A PROGRAM IN MEMORY WHEN ARCHIVING OR UN-ARCHIVING A FILE, "THEN IT WILL ALMOST CERTAINLY BE CLOBBERED BY ┴╥├. " "╫HEN INVOKING THE ┴╥├ COMMAND, ┬┴╙╔├'S POINTERS ARE NOT CHANGED "IN ANY WAY BY ┴╥├. ┘OU MAY HAVE TO TYPE '╬┼╫' BEFORE RUNNING A "PROGRAM AFTER USING THE ┴╥├ COMMAND (OTHERWISE YOU MAY GET AN "'?OUT OF MEMORY' ERROR). " " "╘╚┼╧╥┘ ╧╞ ╧╨┼╥┴╘╔╧╬: "==================== " "┴LL METHODS OF DATA COMPRESSION TAKE ADVANTAGE OF REDUNDANCY OF "ONE FORM OR ANOTHER. ╥UN-LENGTH CODING IS ONE OF THE SIMPLEST, "AND OFTEN THE MOST EFFECTIVE TECHNIQUE. ╟RAPHICS FILES OFTEN "CONTAIN LONG SEQUENCES OF THE SAME BYTE; ZEROS FOR BLANK SPACE, "OR 255S FOR FILLED-IN SPACE. ╥UN-LENGTH CODING RECODES THESE "LONG SEQUENCES AS SHORTER CONTROL SEQUENCES. ╞OR EXAMPLE, A "GRAPHICAL IMAGE STORED IN ╥┴═ MAY LOOK SOMETHING LIKE THE "FOLLOWING IF VIEWED WITH THE MACHINE LANGUAGE MONITOR: " " .:2000 00 00 00 00 00 00 00 00 " .:2008 00 00 FF FF FF FF FF 00 " .:2010 00 00 00 00 00 00 00 00 " .:2018 A0 0B FF FF FF FF FF FF AND SO ON.... " "╘HIS COULD BE STORED ON DISK AS THE SEQUENCE: " " FE 00 0A FE FF 05 FE 00 09 A0 0B FE FF 06 " "╘HE FIRST BYTE ($FE) IS A CONTROL CHARACTER. ╫HEN THE UNSQUEEZE "ROUTINE ENCOUNTERS ONE OF THESE, IT GETS THE NEXT TWO CHARACTERS "AND INTERPRETS THEM AS A 'CHARACTER IDENTIFIER' AND A 'COUNT'. "╘HEORY ╧F ╧PERATION "╘HUS, THE FIRST 3-BYTE SEQUENCE IS INTERPRETED AS 10 ZEROS, THE "NEXT 3-BYTE SEQUENCE AS 5 FF'S AND SO ON. ╫HEN A CHARACTER IS "NOT REPEATED, IT IS SIMPLY CODED DIRECTLY TO THE OUTPUT FILE (THE "$A0 AT $2018 IN THE EXAMPLE). ╙O, THE EXAMPLE IS SQUEEZED FROM "32 BYTES DOWN TO 14. " "─ATABASE PROGRAMS OFTEN SACRIFICE DISK SPACE IN ORDER TO GAIN "SPEED. ╥ELATIVE FILES, FOR INSTANCE, STORE THEIR DATA AT THE "BEGINNING OF EACH RECORD, AND PAD THE RECORD WITH ZEROS. ╙INCE "EVERY RECORD IS THE SAME LENGTH, THE ─╧╙ CAN EASILY CALCULATE "WHERE EACH RECORD STARTS AND THUS RANDOMLY SKIP TO ANY RECORD IN "THE FILE. '╘╚┼ ═┴╬┴╟┼╥' (TM), AND OTHER DATABASE PROGRAMS, PAD "THEIR RECORDS WITH SPACES. ╔N EITHER CASE, THERE IS A GREAT DEAL "OF SPACE TO BE GAINED WHEN PACKING THIS TYPE OF FILE. ╫E HAVE "SEEN SOME ─┬┴╙┼ ╔╔╔ FILES IN EXCESS OF 1-MEGABYTE THAT 'CRUNCH' "DOWN TO ONLY 50,000 CHARACTERS OR SO; MOSTLY DUE TO PACKING. " "╘HERE IS ONE SLIGHT PROBLEM WITH THIS METHOD. ╙UPPOSE YOU ARE "USING A ZERO-BYTE AS THE CONTROL CHARACTER. ╔F A SEQUENCE OF "ONLY ONE ZERO IS ENCOUNTERED, YOU CANNOT CODE IT TO THE OUTPUT "FILE SINCE IT WILL BE INTERPRETED AS A CONTROL CHARACTER. ┘OU "MUST SEND A 3-BYTE CONTROL SEQUENCE TO CODE THE SINGLE ZERO. ┴N "EXAMPLE OF THIS WOULD BE AS FOLLOWS: " " .:0801 06 08 01 00 8F 00 0C 08 " .:0809 02 00 8F 00 12 08 03 00 " .:0811 8F 00 00 00 00 00 00 00 AND SO ON.... " "╘HIS WOULD BE STORED ON DISK AS THE SEQUENCE: " " 06 08 01 00 00 01 8F 00 00 01 0C 08 02 00 00 01 " 8F 00 00 01 12 08 03 00 00 01 8F 00 00 07 ..... " "╫E WENT FROM 24 BYTES TO 30! ╬OT MUCH OF A SAVING! " "╔T IS BECAUSE OF THIS PROBLEM WITH PACKING THAT SQUEEZED FILES "ARE OCCASIONALLY SHORTER THAN THEIR SQUASHED EQUIVALENT. " "╚UFFMAN CODING IS SOMEWHAT MORE COMPLEX. ╔T IS PROBABLY THE MOST "ELEGANT OF ALL THE COMPRESSION METHODS USED AND CERTAINLY THE "MOST COMMON. ╔T TAKES ADVANTAGE OF THE FACT THAT SOME CHARACTERS "ARE USED MORE OFTEN THAN OTHERS IN MOST FILES. ╘EXT FILES "CONTAIN MANY SPACES, AND LETTERS LIKE 'A', 'E', OR 'C' ARE MUCH "MORE COMMON THAN 'X', 'Z', OR 'Q'. ╟RAPHICS FILES CONTAIN MANY "ZEROS OR $FF'S AND MACHINE LANGUAGE PROGRAMS TEND TO CONTAIN MORE "╠─┴'S AND ╙╘┴'S THAN ┼╧╥'S OR ╥╧╥'S. " "╙UPPOSE NOW THAT A FILE CONTAINS ONLY THE CHARACTERS 'A' THROUGH "'Z'. ╙INCE THERE ARE ONLY 26 CHARACTERS USED, A 5-BIT BINARY "NUMBER, WHICH CAN TAKE ON 32 POSSIBLE VALUES, WOULD BE MORE THAN "ADEQUATE TO REPRESENT EACH CHARACTER. ╫E COULD ASSIGN A 5-BIT "NUMBER TO EACH OF THE CHARACTERS 'A' TO 'Z' AND GAIN 3 BITS PER "CHARACTER (OR 37.5%). " "╚UFFMAN CODING TAKES THIS ONE STEP FURTHER. " " "╘HEORY ╧F ╧PERATION "╙UPPOSE ALSO THAT SOME OF THE CHARACTERS OCCUR MUCH MORE OFTEN IN "THE FILE THAN DO OTHERS. ╫E COULD GAIN EVEN MORE SPACE IF THE "FREQUENTLY-OCCURRING CHARACTERS WERE ASSIGNED CODES LESS THAN 5 "BITS LONG, AND THE LESS-FREQUENTLY OCCURRING CHARACTERS WERE "ASSIGNED CODES THAT WERE 5 OR MORE BITS LONG. ╘HE ╚UFFMAN "ALGORITHM DOES JUST THAT. " "╘HE ╚UFFMAN ALGORITHM CONVERTS FIXED-LENGTH CODES (8-BIT "CHARACTERS) INTO CODES WHOSE LENGTH IN BITS IS INVERSELY "PROPORTIONAL TO THEIR PROBABILITY OF OCCURRENCE IN THE DATA FILE. "╞OR EXAMPLE, SUPPOSE YOUR DATA FILE LOOKED SOMETHING LIKE THIS: " " ABRACADABRA " "╘HE CHARACTER FREQUENCY DISTRIBUTION IS AS FOLLOWS: " " TOTAL BITS TOTAL BITS " CHARACTER FREQUENCY HUFFMAN CODE UNSQUEEZED SQUEEZED " --------- --------- ------------ ---------- ---------- " A 5 0 8 * 5 = 40 1 * 5 = 5 " B 2 10 8 * 2 = 16 2 * 2 = 4 " R 2 111 8 * 2 = 16 3 * 2 = 6 " C 1 1100 8 * 1 = 8 4 * 1 = 4 " D 1 1101 8 * 1 = 8 4 * 1 = 4 " ALL OTHERS 0 ---------- ---------- " TOTALS: 88 23 " "╫E COULD REPRESENT THIS INFORMATION AS A BINARY TREE: " " C " / " A B /---- D " / / / " ROOT --- --- --- R " "╘O GET THE ╚UFFMAN CODE WE CODE A '0' BIT EACH TIME WE TRAVERSE A "BRANCH TO THE LEFT, AND A '1' BIT EACH TIME WE TRAVERSE A BRANCH "TO THE RIGHT. ╘HUS, THE CODES ARE GENERATED AS IN THE TABLE "ABOVE AND EVERY CHARACTER GETS A UNIQUE CODE. ╘HE DECOMPRESSOR "SIMPLY STARTS AT THE ROOT, READS THE SQUEEZED FILE ONE BIT AT A "TIME, AND MOVES THROUGH THE TREE UNTIL IT REACHES A TERMINAL NODE "AND THEN SENDS THE CHARACTER IN THAT POSITION TO THE OUTPUT FILE. " "╘HE MOST FREQUENTLY-OCCURRING CHARACTERS ARE KEPT CLOSEST TO THE "ROOT AND THUS HAVE SHORTER CODES. ╘HOSE WITH LOWER FREQUENCIES "OF OCCURRENCE ARE KEPT FURTHER AWAY AND GET LONGER CODES. ╘HE "RESULT IS OFTEN A FILE THAT IS SIGNIFICANTLY SHORTER THAN THE "ORIGINAL. " "╫HEN ALL BYTES OCCUR WITH ABOUT THE SAME FREQUENCY, AS IN MACHINE "LANGUAGE PROGRAM FILES, THEN ALL THE CODES ARE ABOUT THE SAME "LENGTH AND NOT MUCH IS GAINED. ╔N FACT, SINCE THE DE-CODING "INFORMATION (THE TREE) MUST BE INCLUDED IN THE OUTPUT FILE, THE "RESULT CAN OFTEN BE LONGER, PARTICULARLY ON SHORT FILES. " "╞OR THOSE OF YOU THAT ARE INTERESTED IN STATISTICS, WE HAVE "INCLUDED A SMALL UTILITY PROGRAM WITH ┴╥├ THAT ANALYZES THE "╘HEORY ╧F ╧PERATION "FREQUENCY DISTRIBUTION OF THE BYTES IN A FILE AND GRAPHICALLY "DISPLAYS THE RESULTS. ╧N THE TOP PORTION OF THE SCREEN YOU WILL "SEE THE FREQUENCY DISTRIBUTION OF THE BYTES IN THE FILE. ╧N THE "BOTTOM PORTION IS A BAR GRAPH REPRESENTING THE LENGTHS OF THE "╚UFFMAN CODES GENERATED BY THE SQUEEZE ALGORITHM. ┴ HUFFMAN CODE "CAN BE ANYWHERE FROM 0 TO 24 BITS IN LENGTH. ┼ACH BIT IN THE "╚UFFMAN CODE IS REPRESENTED BY TWO PIXELS ON THE GRAPHICS SCREEN. " "╘O RUN THE UTILITY YOU MUST HAVE ┴╥├ IN MEMORY. ┼NTER: " " A:ANALYZE [D:]FILENAME " "╘HE PROGRAM WILL THEN READ THROUGH 'D:FILENAME' AND DISPLAY A "FREQUENCY DISTRIBUTION FOR THE FILE. " "┬UT HOW DO WE COME UP WITH THE BEST TREE TO USE TO GENERATE THE "╚UFFMAN CODES? ╔F YOU SIT DOWN AND THINK ABOUT IT, YOU WILL "REALIZE THAT EVEN IF ONLY A DOZEN OR SO BYTES ARE USED, THE "NUMBER OF POSSIBLE TREES IS QUITE LARGE. " "╚UFFMAN SQUEEZING GETS IT NAME FROM THE MAN THAT CAME UP WITH A "SOLUTION TO THIS PROBLEM. ╫E ACTUALLY TRIED TO FIGURE IT OUT FOR "OURSELVES AND ENDED UP UTTERLY CONFUSED UNTIL WE CAME ACROSS "╚UFFMAN'S ARTICLE (*). ╚UFFMAN MAKES IT LOOK SIMPLE. " "╠ETS GO BACK TO OUR PREVIOUS EXAMPLE OF 'ABRACADABRA'. ╫E START "OUT WITH THE FOLLOWING FREQUENCY DISTRIBUTION: " " CHARACTER FREQUENCY " --------- --------- " A 5 " B 2 " R 2 " C 1 " D 1 " "╫E START BY PICKING OFF THE TWO LOWEST FREQUENCIES AND FORMING A "PARTIAL TREE WITH THEM; IN THIS CASE 'C' AND 'D'. ╘HIS GIVES US "A NEW TABLE: " " CHARACTER FREQUENCY " --------- --------- " A 5 " B 2 " R 2 " C,D 2 " "┴ND WE HAVE A PARTIAL TREE: " " D " / " ROOT - C " " " --------------------- "* ╚UFFMAN, ─.┴., '┴ ═┼╘╚╧─ ╞╧╥ ╘╚┼ ├╧╬╙╘╥╒├╘╔╧╬ ╧╞ ═╔╬╔═╒═ "╥┼─╒╬─┴╬├┘ ├╧─┼╙', ╨ROC. ╔╥┼, 40(9), 1098-1101 (1952) "╘HEORY ╧F ╧PERATION "╬OW WE REPEAT THE PROCEDURE. ╘HIS TIME, HOWEVER, WE HAVE MORE "THAN ONE CHOICE. ╫E COULD CHOOSE 'B' AND 'R', OR 'B' AND 'C,D' "OR 'R' AND 'C,D'. ┴S FAR AS THE RESULTANT FILE IS CONCERNED, IT "MAKES NO DIFFERENCE WHICH ONE WE CHOOSE. ╘HE SQUEEZED FILE'S "LENGTH WILL BE THE SAME! ╠ETS DO IT TWO DIFFERENT WAYS JUST TO "SEE WHAT HAPPENS: " " CHARACTER FREQUENCY CHARACTER FREQUENCY " --------- --------- --------- --------- " A 5 A 5 " B,R 4 C,D,R 4 " C,D 2 B 2 " "WHICH GIVES: " " B C R D " / / / / " ROOT - R ROOT - D ROOT - - C " "AND AGAIN: " " CHARACTER FREQUENCY CHARACTER FREQUENCY " --------- --------- --------- --------- " C,D,B,R 6 C,D,B,R 6 " A 5 A 5 " "WHICH GIVES: " " D " / " /--C " / " / B OR: B R D " / / / / / " ROOT -- - R ROOT - - - - C " "┴ND FINALLY WE COMBINE THESE TO GET: " " D " / " /--C " / " A / B OR: A B R D " / / / / / / / " ROOT - - - - -R ROOT - - - - - C " "╫E END UP WITH THE FOLLOWING TABLES: " " CHARACTER FREQUENCY CODE1 CODE2 " --------- --------- ----- ----- " A 5 0 0 " B 2 110 10 " R 2 111 110 " C 1 101 1111 " D 1 100 1110 " " "╘HEORY ╧F ╧PERATION "╔F YOU MULTIPLY THE CODE LENGTH TIMES THE FREQUENCY FOR EACH "CHARACTER AND SUM THE RESULTS, YOU WILL GET THE FILE'S SQUEEZED "LENGTH IN BITS. ┘OU WILL FIND THAT IT IS THE SAME IN BOTH CASES. "┴╥├ WILL, HOWEVER, ALWAYS CHOOSE THE OPTION WHICH RESULTS IN THE "SHORTEST CODE LENGTHS. ┴╥├ ONLY ALLOWS A MAXIMUM CODE LENGTH OF "24 BITS. ╬OTE ALSO THAT THERE ARE A TOTAL OF ONLY 13 BITS ON THE "LEFT, BUT 14 ON THE RIGHT. ╘HIS ALSO MAKES THE LENGTH OF THE "ENCODING TABLE A BIT SHORTER. ╬O PUN INTENDED. " "╙INCE WE ARE BUILDING THE CODES TWO GROUPS AT A TIME, THE TIME "THAT IT TAKES TO GENERATE THE CODES IS DIRECTLY PROPORTIONAL TO "THE NUMBER OF ENTRIES IN THE TABLE. ┴FTER ┴╥├ FINISHES ITS "ANALYZE PASS, YOU WILL NOTICE A DELAY OF A SECOND OR TWO BEFORE "┴╥├ ACTUALLY STARTS SQUEEZING A FILE. ╞OR TEXT FILES, THE DELAY "IS SHORT BECAUSE THE TABLE ISN'T VERY LONG. ╞OR PROGRAMS, "HOWEVER, THE DELAY IS QUITE NOTICEABLE BECAUSE ALL 256 POSSIBLE "BYTE VALUES ARE USUALLY USED. " "╘REES ARE AN EXCELLENT TOOL FOR UNDERSTANDING THE THEORY BEHIND "╚UFFMAN SQUEEZING. ╧DDLY ENOUGH, ┴╥├ DOESN'T USE THIS CONCEPT TO "ANY ADVANTAGE AT ALL. " "╠EMPEL-┌EV-╫ELCH (*), OR ╠┌╫ COMPRESSION IS USED TO 'CRUNCH' "FILES. ╔T IS REALLY QUITE AMAZING SINCE IT ALMOST ALWAYS IS "CHOSEN AS THE MOST EFFICIENT COMPRESSOR AND CAN BE PERFORMED 'ON "THE FLY' WITHOUT FIRST HAVING TO ANALYZE A FILES CONTENTS. ╔T "TAKES ADVANTAGE OF THE FACT THAT CERTAIN SEQUENCES OF BYTES OCCUR "MORE OFTEN THAN OTHERS IN TYPICAL DATA FILES. " "╞OR EXAMPLE, IN AN ┴╙├╔╔ LISTING OF A ┬┴╙╔├ PROGRAM, THE ┬┴╙╔├ "KEYWORDS, ╔╬╨╒╘, ╟╧╘╧, ╟╧╙╒┬ AND OTHERS OCCUR WITH ABUNDANCE. ╔N "THIS DOCUMENT, WORDS LIKE '┴╥├', 'COMPRESS', 'SQUEEZE', OR "CHARACTERS SEQUENCES LIKE '. ' OR ', ' OCCUR QUITE OFTEN. ╔F WE "COULD REPLACE THESE CHARACTER SEQUENCES WITH SHORTER CODES, WE "WOULD END UP WITH A SHORTER OUTPUT FILE. ╫HEN YOU ENTER A LINE "OF ┬┴╙╔├ CODE, THE ┬┴╙╔├ INTERPRETER DOES JUST THAT BY LOOKING TO "SEE IF ANY KEYWORDS IN THE LINE OCCUR IN ITS KEYWORD TABLE. ┴╥├ "DOES SOMETHING SIMILAR, BUT PREPARES THE KEYWORD TABLE FROM "SCRATCH FOR EACH FILE IT CRUNCHES. " "╘HE ╠┌╫ ALGORITHM READS THE INPUT FILE SEQUENTIALLY AND REMEMBERS "SEQUENCES OF CHARACTERS THAT HAVE OCCURRED PREVIOUSLY IN THE FILE "AND REPLACES SUBSEQUENT OCCURRENCES WITH SHORTER CODES. ╔T "PREPARES A 'STRING TABLE' AS IT GOES THROUGH THE FILE WHICH IS "USED TO GENERATE THE CODES. ┴GAIN, WE COULD THINK OF THE STRING "TABLE AS A TREE, BUT THIS TIME IT IS A MUCH MORE COMPLICATED TREE "SINCE EACH NODE CAN HAVE AS MANY AS 256 BRANCHES! " "╠ETS TAKE A SIMPLIFIED EXAMPLE. ╙UPPOSE THAT THE ALPHABET "CONSISTED ONLY OF THE LETTERS 'A', 'B', AND 'C' AND OUR FILE IS "''BABABACABABAA'. ╫E START BY ASSIGNING A CODE TO EACH LETTER IN "OUR ALPHABET. ╘HUS, 'A=1', 'B=2', AND 'C=3'. " " " ---------------------- "* ╫ELCH, ╘ERRY ┴., '┴ ╘┼├╚╬╔╤╒┼ ╞╧╥ ╚╔╟╚ ╨┼╥╞╧╥═┴╬├┼ ─┴╘┴ "├╧═╨╥┼╙╙╔╧╬', ╔┼┼┼ ├╧═╨╒╘┼╥, ╩UNE 1984. "╘HEORY ╧F ╧PERATION "╘HE FIRST CHARACTER WE ENCOUNTER IS AN 'A'. ╔T IS IN THE STRING "TABLE, SO WE SAVE THE 'A' AS A PREFIX STRING AND GET ANOTHER "CHARACTER WHICH WE CALL THE EXTENSION. ╘HE NEXT CHARACTER IS A "'B', SO WE NOW HAVE THE SEQUENCE 'AB', WHICH IS NOT IN THE STRING "TABLE. " "╫HENEVER THE CURRENT 'PREFIX+EXTENSION' STRING WE HAVE IN MEMORY "IS NOT IN THE STRING TABLE, WE DO THREE THINGS. ╫E SEND THE CODE "FOR THE PREFIX TO THE OUTPUT FILE, ADD THE 'PREFIX+EXTENSION' "STRING TO OUR STRING TABLE, AND MAKE THE EXTENSION THE NEW "PREFIX. ╘HUS, WE CODE OUT A '1' AND SET THE PREFIX EQUAL TO '2', "THE CODE FOR 'B' AND ADD 'AB' TO THE STRING TABLE AS CODE 4. " "╫E NOW HAVE 'B' AS THE PREFIX, AND READ IN THE NEXT CHARACTER "FROM THE INPUT FILE AS OUR NEW EXTENSION. ╘HE NEXT CHARACTER IS "AN 'A'. 'BA' IS NOT IN THE STRING TABLE, SO WE CODE OUT THE 'B', "ADD 'BA'=5 TO THE STRING TABLE, AND MAKE 'A' THE NEW PREFIX. " "╬OW IS WHEN IT STARTS TO GET INTERESTING. ╫E NOW HAVE 'A' AS THE "PREFIX AND READ IN 'B' AS THE NEXT EXTENSION. ╘HIS TIME 'AB' IS "IN THE STRING TABLE, SO WE MAKE THE CODE FOR 'AB' THE NEW PREFIX "AND GET ANOTHER EXTENSION. ╘HE NEXT CHARACTER IS AN 'A', 'ABA' IS "NOT IN THE STRING TABLE, SO WE SEND THE PREFIX CODE 'AB'=4 TO THE "OUTPUT FILE AND ADD 'ABA'=6 TO OUR STRING TABLE. ╬EXT TIME WE "ENCOUNTER THE SEQUENCE 'ABA', WE'LL ONLY HAVE TO SEND ONE CODE IN "THE PLACE OF THREE CHARACTERS! " "╘HE PREFIX IS NOW 'A'. ╫E GET THE NEXT CHARACTER 'B'. 'AB' IS "IN THE STRING TABLE, SO WE MAKE 'AB'=4 THE PREFIX AND GET ANOTHER "CHARACTER. ╘HIS TIME IT'S AN 'A'. 'ABA' IS ALSO IN THE STRING "TABLE, SO WE WE MAKE 'ABA'=6 OUR PREFIX AND GET ANOTHER "EXTENSION. ╘HIS TIME ITS A 'C', SO WE CODE OUT THE PREFIX 6 AND "MAKE 'C' THE NEW PREFIX. " "┴T THIS POINT OUR STRING TABLE LOOKS LIKE THIS: " " STRING CODE PREFIX+EXTENSION " ------ ---- ---------------- " A 1 " B 2 " C 3 " AB 4 1+2 " BA 5 2+1 " ABA 6 4+1 " ABAC 7 6+1 " "╧R IF YOU PREFER TREES: " " A=1 - B=4 - A=6 - C=7 " / " ROOT - B=2 - A=5 " \ " C=3 " " " " "╘HEORY ╧F ╧PERATION "╘HIS GOES ON UNTIL THE STRING TABLE IS FULL. ╔F THERE IS ENOUGH "REPETITION IN THE INPUT FILE, LONG SEQUENCES OF CHARACTERS CAN BE "REPLACED BY SHORT 9-12 BIT CODES AND SIGNIFICANT SAVINGS CAN BE "ACHIEVED. " "┴╥├ STARTS OUT BY INITIALIZING ITS STRING TABLE TO 256 ENTRIES; "THE BYTE VALUES 0 TO 255. ╙INCE THE FIRST 256 CODES GENERATED "WILL TAKE ON VALUES BETWEEN 256 AND 511, WE ONLY NEED 9 BITS FOR "THE FIRST 256 CODES. ╘HE NEXT 512 CODES WILL BE BETWEEN 512 AND "1023, SO WE ONLY NEED 10 BITS FOR THE NEXT 512 CODES. ╘HE SIZE "OF THE CODE KEEPS GROWING LIKE THIS UNTIL IT REACHES 12 BITS AND "THE STRING TABLE IS FULL. ╘HIS SIGNIFICANTLY IMPROVES THE "COMPRESSION RATIO WHEN CRUNCHING SMALL FILES. " "╧NCE THE STRING TABLE IS FULL, IF A CHARACTER IS ENCOUNTERED FOR "THE FIRST TIME, IT WILL HAVE TO BE SENT TO THE OUTPUT FILE AS A "12-BIT CODE; A 50% LOSS! ╫E HAVE FOUND THAT THE STRING TABLE "USUALLY FILLS UP AT ABOUT 60-70 ├┬═ DISK BLOCKS FOR TEXT, AND AT "ABOUT 40 FOR MACHINE LANGUAGE. ┘OU MAY NOTICE THAT ═╠ PROGRAMS "OF 40 BLOCKS OR LESS USUALLY CRUNCH, WHEREAS LONGER ═╠ PROGRAMS "TEND TO BE SQUASHED. ╔F YOU ARE CRUNCHING TEXT FILES, THE "COMPRESSION RATIO IS USUALLY ABOUT 2 TO 1. ╧NCE THE STRING TABLE "HAS BECOME FULL, THE COMPRESSION RATIO WILL START TO DIMINISH "BECAUSE OF THIS. " "┴╥├ RESERVES TWO CODES WHEN IT CRUNCHES A FILE. ├ODE 256 IS "RESERVED TO INDICATE THE END OF FILE. ╘HIS IS NECESSARY SINCE "┴╥├ DOESN'T KNOW A FILE'S LENGTH UNTIL AFTER IT HAS BEEN ARCHIVED "USING THE SINGLE PASS CRUNCH OPTION. ├ODE 257 IS RESERVED FOR "FUTURE VERSIONS OF ┴╥├, WHICH WILL USE IT AS A SIGNAL TO TELL THE "DECOMPRESSOR TO RESET THE STRING TABLE ONCE THE COMPRESSION RATIO "STARTS TO FALL OFF ON LARGE FILES. " "┴NOTHER AMAZING THING ABOUT CRUNCHING IS THE FACT THAT IT IS NOT "VERY EFFICIENT! ╬O ATTEMPT IS MADE TO FIND THE MOST OFTEN "OCCURING CHARACTER SEQUENCES IN THE FILE. ╘HE ╠┌╫ APPROACH "SIMPLY TAKES THINGS AS THEY COME. ┴ LONG AND VERY INFREQUENTLY "OCCURING CHARACTER SEQUENCE COULD BE TAKING UP VALUABLE SPACE IN "THE STRING TABLE, WHEN OTHER FREQUENTLY OCCURRING SEQUENCES HAVE "TO BE CODED AS INDIVIDUAL CODES ONCE THE TABLE IS FULL. ╫HEN A "FILE IS VERY LONG, THE STRING TABLE MAY HAVE GIVEN A GOOD "COMPRESSION RATIO NEAR THE BEGINNING OF THE FILE BUT THE STRING "TABLE MAY NO LONGER REFLECT THE FILES CHARACTERISTICS NEAR THE "END OF THE FILE. " "─ESPITE THE FACT THAT CRUNCHING GIVES QUITE GOOD COMPRESSION "RATIOS, THERE IS LOTS OF ROOM FOR IMPROVEMENT. ╫E COULD BE MORE "SELECTIVE ABOUT THE STRINGS WE ALLOW IN THE TABLE, WE COULD PURGE "THE TABLE PERIODICALLY FOR INFREQUENTLY USED CODES, OR WE COULD "SIMPLY USE A LARGER STRING TABLE. " " " " " " " "┴RCHIVE ╞ILE ╞ORMAT "* ┴╥├╚╔╓┼ ╞╔╠┼ ╞╧╥═┴╘: " "┼ACH ARCHIVE ENTRY CONSISTS OF A SHORT HEADER FOLLOWED BY THE "COMPRESSED FILE. ╔F THE FILE IS SQUEEZED OR SQUASHED, THE "╚UFFMAN ENCODING TABLE APPEARS IMMEDIATELY FOLLOWING THE HEADER "AND BEFORE THE FILE DATA. ╘HE ARCHIVE HEADER CONSISTS OF THE "FOLLOWING BYTES: " " OFFSET LENGTH DESCRIPTION " ------ ------ ----------- " 0 1 VERSION 1 FOR ┴╥├ 1.XX " 2 FOR ┴╥├ 2.XX " 1 1 STORAGE 0=STORE 1=PACK " 2=SQUEEZ 3=CRUNCH " 4=SQUASH 5=1 PASS CRUNCH " 2 2 CHECKSUM LO,HI " 4 3 ORIGINAL LENGTH-(BYTES) LO,MID,HI " 7 2 SQUEEZED LENGTH-(BLOCKS) LO,HI " 9 1 FILE TYPE S, P, U, OR R " 10 1 LENGTH OF FILENAME " 11 N FILENAME " "╘HE FOLLOWING ADDITIONAL BYTES OCCUR IF VERSION IS 2 OR HIGHER: " " 11+N 1 RECORD LENGTH IF RELATIVE FILE " (254 OTHERWISE) " 11+N+1 2 DATE IN ═╙-─╧╙ FORMAT " BITS: 0-4 = DAY " 5-8 = MONTH " 9-15= YEAR-1980 " "╘HE FILE DATA FOLLOWS STARTING AT OFFSET '11+N+2'. " "╔F THE FILE IS STORED, THEN A COPY OF THE FILE FOLLOWS. ╘HE "NUMBER OF BYTES ARE SPECIFIED AT OFFSET 4 IN THE HEADER. " "╔F THE FILE IS PACKED, THEN ┴╥├S NUMBERED 1.XX WILL CHOOSE THE "BYTE WHICH OCCURS LEAST OFTEN IN THE FILE AS THE CONTROL "CHARACTER. ┴╥├S NUMBERED 2.XX ALWAYS USE 254 AS THE CONTROL "CHARACTER. ╘HE CONTROL CHARACTER IS STORED AT OFFSET '11+N+2' IN "THE HEADER AND IS FOLLOWED BY THE PACKED FILE. ┴ CONTROL "SEQUENCE IS <CONTROL CHAR> <COUNT> <CHARACTER TO REPEAT>. "'├OUNT' CAN BE BETWEEN 3 AND 256, WITH 0 BEING 256. ┴╥├S "NUMBERED LESS THAN 2.00 HAD A BUG IN THE PACK ROUTINES. ╘O "COMPENSATE FOR THIS BUG, A COUNT OF ZERO SHOULD BE REPLACED BY A "COUNT OF 255, AND THE FILE WILL UN-PACK PROPERLY. ╘HIS BUG HAS "BEEN CORRECTED IN ┴╥├S NUMBERED 2.00 OR HIGHER. " "╔F THE FILE IS SQUEEZED, SQUASHED OR CRUNCHED, THEN IT MUST BE "READ ONE BIT AT A TIME FROM HERE ON IN. ┴╥├ FILLS A BYTE FROM "RIGHT TO LEFT, SO THE BITS WILL APPEAR DIFFERENTLY IF YOU LOOK AT "THEM WITH A DISK DOCTOR, BUT THIS IS THE ORDER IN WHICH THEY ARE "WRITTEN TO THE FILE. " " " " "┴RCHIVE ╞ILE ╞ORMAT "* ╙╤╒┼┼┌┼─ ╞╔╠┼ ┼╬├╧─╔╬╟ ╘┴┬╠┼: " " ╠0 ├0 ╠1 ├1 ╠2 ├2 ... ╠255 ├255 " "╙INCE EACH CODE CAN BE AS LONG AS 24 BITS, EACH LENGTH IS 5 BITS "LONG. ╘HUS ╠0 IS THE LENGTH OF THE ╚UFFMAN CODE FOR ┴╙├╔╔ 0, AND "├0 IS THE ACTUAL ╚UFFMAN CODE. ╘HE TOTAL LENGTH OF THE ENCODING "TABLE IS THEN: " " (5 * 256) + SUM(CODE LENGTHS) ... IN BITS " "╔F AN ┴╙├╔╔ VALUE DOES NOT OCCUR IN THE FILE, ITS CODE LENGTH "WILL BE ZERO AND THE BIT IMMEDIATELY FOLLOWING WILL BE THE LENGTH "FOR THE NEXT ┴╙├╔╔ VALUE. ╘HIS IS WHY, WHEN YOU SQUEEZE A TEXT "FILE, THERE ARE A LOT OF ZEROS NEAR THE BEGINNING OF THE ARCHIVE "ENTRY. ╘HERE ARE A LOT OF UNUSED ┴╙├╔╔ VALUES. " "╔MMEDIATELY FOLLOWING THE LAST ┬╔╘ OF THE ENCODING TABLE IS THE "ACTUAL FILE REPRESENTED BY ITS ╚UFFMAN CODES. " "╫HEN UNSQUEEZING A FILE, ┴╥├ READS IN THE LENGTHS AND CODES AND "INSERTS THEM INTO TABLES SO THAT THEY REMAIN SORTED ON THE CODE "LENGTH. ╔F OUR TREE WAS: " " E M P A " / / / / " ROOT - - - - R " "THE TABLES WOULD LOOK LIKE THIS AFTER READING THE ENCODING TABLE: " " ┴╙├╔╔ LENGTH CODE " ----- ------ -------------------------- " E 1 00000000 00000000 00000000 " M 2 00000000 00000000 00000010 " P 3 00000000 00000000 00000110 " A 4 00000000 00000000 00001110 " R 4 00000000 00000000 00001111 " "╘HE WORD 'AMPERE' WOULD BE STORED ON DISK AS: " " 1110 10 110 0 1111 0 " "╘O READ IN A ╚UFFMAN CODE, RESET YOUR TEST CODE TO ALL ZEROS, "START AT THE BEGINNING OF THE TABLE, AND SHIFT IN ONE BIT AT A "TIME FROM THE SQUEEZED FILE INTO THE TEST CODE. ╘HE ╚UFFMAN "INPUT ROUTINE WOULD BE SOMETHING LIKE THIS: " " TEST = 00000000 00000000 00000000 " OFFSET = 0 " 1.0 SHIFT BIT INTO TEST " 1.1 IF LENGTH(OFFSET) < LENGTH OF TEST THEN ERROR " (CAN'T HAPPEN) " IF LENGTH(OFFSET) > LENGTH OF TEST THEN 1.0 " IF TEST=CODE(OFFSET) THEN OUTPUT ASCII(OFFSET) AND EXIT " OFFSET=OFFSET+1 " IF OFFSET > NUMBER OF CODES THEN ERROR (CAN'T HAPPEN) " GOTO 1.1 "╫HAT ═AKES ┴╥├ ╘ICK? "╘HE ROUTINE WORKS BECAUSE NO CODE CAN BE A SUBSTRING OF ANOTHER "CODE. ╘HAT IS, IF ONE OF THE CODES IS '01', THEN ANY OTHER CODE "STARTING WITH THE BIT SEQUENCE '01' CANNOT OCCUR. " "╘HIS ISN'T THE MOST EFFICIENT WAY TO DO IT, BUT IT WORKS! ╫HEN A "╚UFFMAN CODE THAT HAS THE MAXIMUM LENGTH COMES IN, THE ROUTINE "HAS TO TEST EACH AND EVERY ONE OF THE CODES IN THE TABLE! "╚OWEVER, THE MOST FREQUENTLY OCCURING CHARACTERS IN THE FILE WILL "OCCUR NEAR THE BEGINNING OF THE TABLE, SO IT ISN'T ALL THAT BAD. " "╫HEN UN-SQUASHING A FILE, YOU PROCEED EXACTLY THE SAME WAY, "EXCEPT ONCE YOU UNSQUEEZE IT YOU HAVE TO UN-PACK IT AS WELL. ╘HE "CONTROL CHARACTER FOR PACKING IS ALWAYS '$FE' IN SQUASHED OR "CRUNCHED FILES. " "┴FTER THE HEADER, THE CRUNCHED FILE APPEARS AS A SEQUENCE OF "CODES. ╘HE CODES ARE ORIGINALLY 9 BITS IN LENGTH AND GROW TO A "LENGTH OF 12 BITS. ╘HE SPECIAL RESERVED CODE OF 256 APPEARS AS "THE END OF FILE MARKER. ╞ILES THAT HAVE BEEN CRUNCHED IN 1 PASS "ARE IDENTICAL TO FILES THAT HAVE BEEN CRUNCHED IN 2 PASSES, "EXCEPT THAT THE FILE'S LENGTH AND CHECKSUM WILL APPEAR TO BE ZERO "IN THE HEADER FOR 1-PASS CRUNCHED FILES. ╔F THE FILE WAS "CRUNCHED IN 1 PASS, THEN THE ORIGINAL LENGTH AND CHECKSUM FOLLOW "THE END OF FILE MARKER. " " "* ╫╚┴╘ ═┴╦┼╙ ┴╥├ ╘╔├╦? " "╘HE FOLLOWING PSUEDO-CODE SHOULD MAKE IT FAIRLY CLEAR AS TO WHAT "┴╥├ IS DOING WHEN CREATING OR EXTRACTING AN ARCHIVE. ╫E GET A "LOT OF QUESTIONS ALONG THESE LINES. ╚OPEFULLY THIS SECTION WILL "ANSWER SOME OF THEM. " "┬UT FIRST WE'LL DEFINE SOME OF THE TERMINOLOGY WE WILL BE USING. "╘HE GENERAL FORMAT FOR THE ┴╥├ COMMAND IS: " " ┴╥├/╪┘/┌ ─:┴╥├╬┴═┼ ─:╨┴╥═1 ─:╨┴╥═2 ..... " "╘HE COMMAND LINE IS THE COMMAND THAT YOU TYPED IN TO GET ┴╥├ "GOING. ╔T IS SIMPLY A SERIES OF CHARACTER STRINGS SEPARATED BY "SPACES. ╘HE FIRST CHARACTER STRING ON THE COMMAND LINE, "'┴╥├/╪┘', IS OF COURSE THE COMMAND. '╪' AND '┘' ARE CALLED "SWITCHES. ╫E'LL CALL '╪' SWITCH 1, '┘' SWITCH 2, AND '┌' SWITCH "3. " "╘HE REMAINING STRINGS ON THE COMMAND LINE ARE CALLED PARAMETERS. "╘HUS, '─:┴╥├╚╬┴═┼' IS PARAMETER NUMBER 1, '─:╨┴╥═1' IS PARAMETER "NUMBER 2, AND SO ON. ┴╥├ ALLOWS FOR A MAXIMUM OF 10 PARAMETERS "(0-9) INCLUDING THE COMMAND ITSELF, WHICH IS PARAMETER NUMBER "ZERO. " "╬OTE THAT SPACES ARE NOT ALLOWED WITHIN A PARAMETER, AS ┴╥├ WILL "INTERPRET THIS AS BEING TWO SEPARATE PARAMETERS. ╔F YOU WANT TO "SPECIFY A FILE NAMED '╧╬┼ ╘╫╧ ╘╚╥┼┼', THERE ARE TWO POSSIBILIES; "YOU COULD SPECIFY IT USING WILDCARDS AS '╧╬┼?╘╫╧?╘╚╥┼┼', OR YOU "COULD USE ╙╚╔╞╘ED SPACES INSTEAD OF SPACES IN THE FILENAME; ┴╥├ "WILL CHANGE THEM TO SPACES AND GET THE CORRECT FILE. "╫HAT ═AKES ┴╥├ ╘ICK? "╫HEN YOU HIT ╥┼╘╒╥╬, ┴╥├ DOES THE FOLLOWING: " ╟┼╘ SWITCH 1 " ╘┼╙╘ SWITCH 1 FOR VALID CHARACTER... ┴,├,╞,╠,╨ OR ╓ " ╔╞ SWITCH 1 IS INVALID THEN ABORT. " ╟┼╘ PARAMETER 1 " ╔╞ NO PARAMETER 1 ╘╚┼╬ " ABORT. " ┼╠╙┼ " ADD .ARC EXTENSION TO PARAMETER 1 IF REQ'D " ╔╞ SWITCH 1 IS ┴ OR ├ ╘╚┼╬ " OPEN ARCHIVE FOR WRITE " ┼╠╙┼ " OPEN ARCHIVE FOR READ " ┼╬─╔╞ " ┼╬─╔╞ " " ╔╞ SWITCH 1 IS AN ┴ OR A ├ THEN CREATE ARCHIVE " ╔╞ SWITCH 1 IS AN ╪, ╨, OR ╓ THEN EXTRACT ARCHIVE " ╔╞ SWITCH 1 IS AN ╠ THEN ARCHIVE DIRECTORY " ╔╞ SWITCH 1 IS AN ╞ THEN FIX ╪═╧─┼═ PADDING " " "* ├╥┼┴╘┼ ┴╥├╚╔╓┼ "----------------------------------------------------------------- " ╫╚╔╠┼ STILL MORE PARAMETERS (2,3,4,...9) " ═AKE A DIRECTORY NAME ($D:XXXX) OUT OF THE " PARAMETER AND LOAD THE DIRECTORY INTO ╥┴═. " ╞╧╥ EACH FILENAME IN THE DIRECTORY " 1) ANALYZE THE FILE " 2) COMPRESS THE FILE USING " THE BEST COMPRESSOR " ╬┼╪╘ FILE " ╬┼╪╘ PARAMETER " ┼╬─╫╚╔╠┼ " ├LOSE ARCHIVE " ╙╘╧╨ " " "* ┴╬┴╠┘┌┼ ╘╚┼ ╞╔╠┼: "----------------------------------------------------------------- " ╧╨┼╬ THE FILE TO BE ANALYZED FOR READ " ╙┼╘ STORED, PACKED, SQUEEZED, SQUASHED, AND CRUNCHED " LENGTHS TO ZERO " ╙┼╘ THE CHECKSUM TO ZERO " ╙┼╘ THE SQUEEZE AND SQUASH FREQUENCY DISTRIBUTIONS " TO ZERO " ╞╧╥ EACH BYTE IN THE FILE " ╔NCREMENT THE STORED (ORIGINAL) LENGTH " ┴DJUST THE CHECKSUM " ┴DJUST THE SQUEEZE FREQUENCY DISTRIBUTION " ╔╞ OUTPUT REQUIRED FOR ╨┴├╦ ╘╚┼╬ " ╔NCREMENT THE PACKED FILES LENGTH " ┴DJUST THE SQUASH FREQUENCY DISTRIBUTION " ╔╞ OUTPUT REQUIRED FOR ├╥╒╬├╚ ╘╚┼╬ " ┴DJUST THE CRUNCHED FILES LENGTH " ╬┼╪╘ BYTE " ├╠╧╙┼ INPUT FILE "╫HAT ═AKES ┴╥├ ╘ICK? " ╟ENERATE THE SQUEEZE ╚UFFMAN CODES AND CALCULATE " THE SQUEEZED FILE LENGTH AS " SUM(CODE LENGTH * FREQUENCY)+HEADER " ╟ENERATE THE SQUASH ╚UFFMAN CODES AND CALCULATE " THE SQUASHED FILE LENGTH AS " SUM(CODE LENGTH * FREQUENCY)+HEADER " ├ALCULATE WHICH IS THE SHORTEST LENGTH " STORE, PACK, SQUEEZE, SQUASH, OR CRUNCH " ─╧╬┼ ANALYZING THE FILE " " "* ├╧═╨╥┼╙╙ ╘╚┼ ╞╔╠┼: "----------------------------------------------------------------- " ╫RITE THE FILE HEADER " ╔F THE FILE IS PACKED THEN WRITE THE CONTROL CHARACTER " (ALWAYS 254 FOR VERSION 2.XX) ╓ERSION 1.XX SELECTS " THE BYTE WHICH OCCURS LEAST OFTEN IN THE INPUT FILE " AS THE CONTROL CHARACTER " ╔F THE FILE IS SQUEEZED OR SQUASHED THEN WRITE THE " APPROPRIATE ╚UFFMAN ENCODING TABLE " ╧╨┼╬ THE FILE TO BE COMPRESSED " ╞╧╥ EACH BYTE IN THE FILE " ╟┼╘ THE BYTE " ├OMPRESS THE BYTE USING SELECTED METHOD " ╬┼╪╘ BYTE " ├╠╧╙┼ THE INPUT FILE " ╔╞ CRUNCHING FILE THEN SEND END OF FILE MARKER " ╔╞ CRUNCHING IN ONE PASS THEN ALSO SEND ORIGINAL " LENGTH AND CHECKSUM. (BOTH OF WHICH ARE NOT " KNOWN UNTIL NOW) " ─╧╬┼ COMPRESSING FILE. ╨AD THE COMPRESSED LENGTH TO AN " EVEN MULTIPLE OF 254 BYTES AND EXIT SUBROUTINE " " "* ┼╪╘╥┴├╘ ┴╥├╚╔╓┼: "----------------------------------------------------------------- " ┴RCHIVE IS OPEN FOR READ, SO: " ╫╚╔╠┼ ╬╧╘ END OF FILE " ╟┼╘ HEADER FOR THIS ENTRY " ╔╞ NO HEADER, OR ERROR IN HEADER ╘╚┼╬ ABORT " ╔╞ LENGTH OF THIS BLOCK IS < 254 ╘╚┼╬ ABORT " (THIS WILL IGNORE ANY ╪═╧─┼═ PADDING) " ╔╞ NAME IN HEADER MATCHES ANY PARAMETER 2-9 ╘╚┼╬ " ├┴╠╠ EXTRACT FILE SUBROUTINE " ┼╠╙┼ " GET NUMBER OF BLOCKS TO SKIP FROM HEADER " AND SKIP THAT MANY BLOCKS " ┼╬─╔╞ " ╔╞ HEADER CHECKSUM=NEW CHECKSUM ╘╚┼╬ " ╨╥╔╬╘ 'OK.' " ┼╠╙┼ " ╨╥╔╬╘ 'CHECKSUM ERROR.' " ┼╬─╔╞ " ┼╬─╫╚╔╠┼ " ─╧╬┼ EXTRACTING ARCHIVE " " "╫HAT ═AKES ┴╥├ ╘ICK? "* ┼╪╘╥┴├╘ ╞╔╠┼...╙UBROUTINE FOR ┼╪╘╥┴├╘ ┴╥├╚╔╓┼ "----------------------------------------------------------------- " ╔╞ SWITCH 1 IS ╪ ╘╚┼╬ OPEN FILE FOR WRITE " ╟┼╘ FILE'S ORIGINAL LENGTH FROM ARCHIVE HEADER " ╙┼╘ NEW CHECKSUM TO ZERO " ╫╚╔╠┼ ORIGINAL LENGTH > 0 ─╧ " ─┼COMPRESS A BYTE " ┴─╩╒╙╘ NEW CHECKSUM " ╔╞ SWITCH 1 IS ╪ ╘╚┼╬ WRITE BYTE TO OUTPUT FILE " ╔╞ SWITCH 1 IS ╨ ╘╚┼╬ " ╔╞ SWITCH 2 IS ╨ ╘╚┼╬ CONVERT ASCII TO PETSCII " ╔╞ SWITCH 2 IS ┴ ╘╚┼╬ CONVERT PETSCII TO ASCII " ╔╞ SWITCH 3 IS ╨ ╘╚┼╬ " OUTPUT TO PRINTER " ┼╠╙┼ " OUTPUT TO SCREEN " ┼╬─╔╞ " ┼╬─╔╞ " ─┼├REMENT ORIGINAL LENGTH " ┼╬─ ╫╚╔╠┼ " ╔╞ FILE OPEN FOR WRITE ╘╚┼╬ CLOSE IT " ╥┼╘╒╥╬ FROM SUBROUTINE " " "* ╞╔╪ ╪═╧─┼═ ╨┴──╔╬╟: "----------------------------------------------------------------- "┴RCHIVE IS OPEN FOR READ, SO WE KNOW IT EXISTS. " " ├LOSE THE ARCHIVE. " " ╟┼╘ TRACK,SECTOR WHERE ARCHIVE STARTS FROM THE " DIRECTORY " " ╟┼╘ TRACK,SECTOR " ╔╞ TRACK LINK <> 0 ╘╚┼╬ " ╟┼╘ TRACK,SECTOR=LINK " ┼╠╙┼ " ╫E'RE AT THE LAST BLOCK OF THE FILE SO: " ╔╞ SECTOR LINK = 255 ╘╚┼╬ " ╨╥╔╬╘ 'ARCHIVE IS OK.' " ┼╠╙┼ " ╟┼╘ PREVIOUS TRACK,SECTOR AND CHANGE " LINK TO 0,255 " ╨╥╔╬╘ 'ARCHIVE HAS BEEN REPAIRED.' " ┼╬─╔╞ " ┼╬─╔╞ " " ─╧╬┼ FIXING ARCHIVE " " " " " " " " " "╘RICKS ┴ND ╘IPS "┴╥├ ╘╥╔├╦╙ ┴╬─ ╘╔╨╙: "==================== " "1) ═┴╬╔╨╒╠┴╘╔╬╟ ┴╥├╚╔╓┼╙ " "╔F YOU WERE TO USE A DISK DOCTOR TO LOOK AT AN ARCHIVE, YOU WOULD "NOTICE THAT EVERY FILE IN THE ARCHIVE STARTS AT THE BEGINNING OF "A ├┬═ DISK SECTOR AND STOPS AT THE END OF A SECTOR. ╘HIS FACT "CAN BE USED TO ADVANTAGE, AND WILL BE IN FUTURE ┴╥├S, IN A NUMBER "OF WAYS. " "╞IRST OF ALL, IT MAKES IT POSSIBLE TO BREAK AN ARCHIVE UP INTO A "NUMBER OF SMALLER ARCHIVES SIMPLY BY MANIPULATING THE DIRECTORY "AND A FEW TRACK,SECTOR LINKS. ╙INCE IT IS NOT NECESSARY TO MOVE "ANY DATA, THIS SHOULD BE A RELATIVELY FAST PROCEDURE. ┘OU COULD "SPLIT AN ARCHIVE INTO TWO WITH A DISK DOCTOR AS FOLLOWS: " " 1) CREATE A DUMMY FILE ON THE SAME DISK AS THE ARCHIVE " 2) SCRATCH THE DUMMY FILE " 3) LOCATE THE ARCHIVE AND FOLLOW THE SECTOR LINKS UNTIL " YOU SEE THE FILENAME OF THE ARCHIVE ENTRY WHICH IS " TO BE THE FIRST FILENAME IN THE SECOND ARCHIVE " 4) JOT DOWN THE TRACK AND SECTOR YOU ARE LOOKING AT " 5) BACKUP TO THE PREVIOUS SECTOR AND CHANGE THE LINK " TO 0,255 " 6) GET BACK TO THE DIRECTORY AND LOCATE THE DUMMY " FILE FROM (1) " 7) CHANGE THE FILETYPE FROM DELETED (0) TO PROGRAM (130) " 8) CHANGE THE TRACK,SECTOR TO THE ONES YOU JOTTED DOWN " IN STEP 4 ABOVE " "┘OU NOW HAVE TWO SEPARATE ARCHIVES. ╘HE BLOCK COUNT FOR THESE "FILES WILL NOT BE CORRECT IN THE DIRECTORY, AND SHOULD BE FIXED, "BUT NO ERRORS SHOULD ARISE IF THEY ARE NOT. " "┴ SIMILAR PROCEDURE COULD BE USED TO DELETE AN ARCHIVE ENTRY. "╙IMPLY MANIPULATE THE SECTOR LINKS TO POINT AROUND THE ENTRY TO "BE DELETED AND THEN VALIDATE THE DISK. " "┘OU COULD ALSO RE-ARRANGE THE ORDER OF THE ARCHIVE ENTRIES IN AN "ARCHIVE, APPEND ONE ARCHIVE TO ANOTHER, TRANSFER AN ARCHIVE ENTRY "TO ANOTHER ARCHIVE AND SO ON AND SO FORTH. ┴LL OF THIS COULD BE "DONE WITHOUT HAVING TO MOVE A SINGLE BYTE OF DATA! " " "2) ╥┴╬─╧═ ┴├├┼╙╙ ┴╥├╚╔╓┼╙: " "┴N ARCHIVE COULD BE MADE RANDOM ACCESS IN EACH OF TWO WAYS: " "1) ╘HE FIRST METHOD WOULD BE TO FOLLOW THE TRACK,SECTOR LINKS " AND READ THE NUMBER OF ├┬═ DISK BLOCKS IN EACH ARCHIVE ENTRY. " ╘HIS INFORMATION COULD THEN BE USED TO CALCULATE WHERE EACH " ARCHIVE ENTRY BEGINS. " "2) ┴ SECOND METHOD WOULD BE TO CONVERT THE ARCHIVE TO A RELATIVE " FILE. ╙IMPLY CREATE THE ARCHIVE BY NORMAL PROCEDURES, AND " THEN USE ┴╥├ TO ARCHIVE THE ARCHIVE YOU JUST CREATED. ╬OW "╘RICKS ┴ND ╘IPS " LOAD AND RUN YOUR FAVORITE DISK SECTOR EDITOR AND VIEW THE " FIRST SECTOR OF THE ARCHIVE OF THE ARCHIVE. ├HANGE THE " FILE'S TYPE TO '╥' FOR ╥┼╠ATIVE IN THE ARCHIVE HEADER. (┘OU " WILL SEE THE FILETYPE AS A '╨', 2 BYTES BEFORE THE FILENAME). " " ╬OW, ALL YOU HAVE TO DO IS UN-ARCHIVE IT AND IT WILL BECOME A " RELATIVE FILE WITH RECORD LENGTH 254 AND CAN BE ACCESSED " RANDOMLY. " "┬UT WHY WOULD YOU WANT A RANDOM ACCESS ARCHIVE ANYWAY? " "╫E PLAN TO WRITE A SIMPLE UN-SQUASH ROUTINE THAT CAN BE ACCESSED "AS A SUBROUTINE BY A ┬┴╙╔├ OR ═ACHINE ╠ANGUAGE PROGRAMMER. "╒NFORTUNATELY THE ├╥╒╬├╚ ROUTINES REQUIRE A GREAT DEAL OF "WORKSPACE (ABOUT 28╦) AND WOULD NOT BE OF MUCH USE TO MOST "APPLICATIONS. ╚OWEVER, A SMALL ROUTINE COULD RESIDE INSIDE ABOUT "2╦ BYTES WHICH WOULD UN-PACK, UN-SQUEEZE, OR UN-SQUASH AN "ARCHIVE. " "╔F YOUR APPLICATION REQUIRES A LARGE NUMBER OF GRAPHICS SCREENS, "OR A GREAT DEAL OF TEXT, YOU COULD CRAM AT LEAST TWICE AS MUCH "INFORMATION ON A DISK USING RANDOM ACCESS ARCHIVES! " " "├╚╧╧╙╔╬╟ ╘╚┼ ├╧═╨╥┼╙╙╧╥ ═┴╬╒┴╠╠┘: "================================= " "┴╥├ NOW LETS YOU CHOOSE THE METHOD OF STORAGE YOURSELF. ╘HE MOST "USEFUL OPTION IS WHEN YOU OPT TO CRUNCH ALL FILES IN A SINGLE "PASS. ╔F DISK STORAGE IS A CONSIDERATION, THEN THE FOLLOWING "RULES OF THUMB CAN BE USED TO DECIDE WHEN TO CHOOSE THIS OPTION "AND WHEN TO AVOID IT. " "╔F YOU LET ┴╥├ CHOOSE THE MOST EFFICIENT COMPRESSOR, THEN YOU "WILL FIND THAT: " " 1) ╘EXT FILES ALMOST ALWAYS ├╥╒╬├╚ " 2) ╫ORD╨RO (TM) OR ╨APER├LIP (TM) FILES ALMOST ALWAYS ├╥╒╬├╚ " 3) ┬┴╙╔├ PROGRAMS ALMOST ALWAYS ├╥╒╬├╚ " 4) ═ACHINE LANGUAGE PROGRAMS LESS THAN 40 BLOCKS WILL " USUALLY ├╥╒╬├╚ AND SOMETIMES ╙╤╒┴╙╚ " 5) ╠ARGER ═╠ PROGRAMS USUALLY ╙╤╒┴╙╚ AND OCCASIONALLY " ╙╤╒┼┼┌┼ OR ╨┴├╦ " 6) ╟RAPHICS IMAGES EITHER ├╥╒╬├╚ OR ╙╤╒┴╙╚ (50:50) " AND OCCASIONALLY ╨┴├╦ " "┴T PRESENT THERE ARE NO VERSIONS OF ┴╥├ FOR ├OMMODORE COMPUTERS "OTHER THAN THE 64. ┼VENTUALLY, THERE WILL BE AT LEAST A PROGRAM "THAT WILL EXTRACT ARCHIVES ON A ╨┼╘, ╓╔├ OR WHAT HAVE YOU. " "╘HE ├╥╒╬├╚ ROUTINES REQUIRE A LARGE AMOUNT OF ╥┴═ MEMORY (ABOUT "32╦ OR MORE), SO IF YOU ARE ARCHIVING MATERIAL FOR A ╨┼╘ OR ╓╔├ "OR ANY OTHER MACHINE THAT HAS LESS THAN 32╦ ╥┴═, YOU SHOULD AVOID "├╥╒╬├╚ING FILES. " " "