ĐACK ŇAT 64 BY ×ARD Ć. ÓHRAKE ĐACK ŇAT 64 IS A UNIQUE UTILITY PROGRAM THAT ANALYZES AND CORRECTS THE "BLOCKS FREE" ON ANY 1541-FORMATTED DISK. ÍANY COMMERCIAL DISKS ONLY USE A FRACTION OF THE TOTAL SPACE AVAILABLE, LEAVING AMPLE ROOM FOR OTHER PROGRAMS OR INFORMATION, WHICH MANY PEOPLE WOULD LIKE TO USE. ČOWEVER, SINCE MANY OF THESE DISKS ARE COPY-PROTECTED, YOU CAN'T SAFELY USE THIS FREE SPACE. ÉF YOU TRY TO, WITHOUT USING ĐACK ŇAT 64 FIRST, YOU RISK LOSING THE INFORMATION ALREADY ON THAT DISK. ÂY USING ĐACK ŇAT 64 TO ANALYZE AND CORRECT YOUR DISKS, YOU CAN SAFELY PUT MORE THAN ONE PROGRAM ON MOST OF YOUR COMMERCIAL DISKS. ×ITH A BIT OF CREATIVITY, YOU CAN EVEN PUT A MENU PROGRAM ON THE DISK AS WELL, TO LET YOU SELECT WHICH PROGRAM YOU WANT TO USE! ĐACK ŇAT 64 WAS MADE TO BE USED WITH DISK-MENU PROGRAMS, SUCH AS THE AUTHOR'S "ÁUTO- ÍENU" OR "ÇENERIC ÄISKÍENU", AVAILABLE WITH "ÁUTOÂOOT ĆACTORY" ON THE ÎOVEMBER/ÄECEMBER 1991 ŇEŇUN DISK. ŮOU CAN ALSO USE ĐACK ŇAT 64 ON YOUR OWN DISKS, EITHER RIGHT AFTER YOU'VE FORMATTED THEM, OR WHEN THEY START TO DEVELOP BAD SPOTS, SUCH AS READ ERRORS IN A SECTOR OR TWO. ĎNE OF ĐACK ŇAT'S MAIN FUNCTIONS IS TO FIND AND IDENTIFY READ ERRORS IN A BLOCK, AND MARK IT AS A BLOCK THAT HAS ALREADY BEEN USED. ÔHIS ISOLATES THE READ ERROR, AND MAKES THE REST OF THE DISK SAFE TO USE AGAIN. ŐSING ĐACK ŇAT 64 TO ANALYZE YOUR DISKS ĐACK ŇAT 64, AS ANY GOOD PROGRAM SHOULD, THINKS FOR ITSELF WHERE IT CAN, SAVING YOU HASSLE. ŮOU JUST SELECT IT FROM ÍENU 64, OR A WORK DISK, AND FOLLOW THE ON-SCREEN PROMPTS. ÉNSERT THE DISK YOU WANT TO CORRECT WHEN PROMPTED, PRESS A KEY, AND WAIT WHILE THE PROGRAM SCANS AND ANALYZES THE DISK. ÉT'S A RELATIVELY FAST PROCESS, CONSIDERING IT HAS TO ANALYZE YOUR ENTIRE DISK. ÔHE WHOLE OPERATION NORMALLY ONLY TAKES A FEW MINUTES PER DISK. ÁLTHOUGH ĐACK ŇAT 64 WORKS WITH COMMERCIAL DISKS, IT IS ALWAYS SAFEST TO MODIFY ONLY YOUR ARCHIVAL BACKUP DISKS, KEEPING YOUR VALUED ORIGINALS SAFELY STORED AWAY. ×ITH MANY TITLES BECOMING RARER AND HARD-TO-FIND, TREAT YOUR ORIGINAL DISKS WITH ALL THE CARE YOU WOULD FOR A VALUED MUSIC RECORDING COLLECTION, OR OUT-OF-PRINT BOOKS. ×ITH REASONABLE CARE, YOUR Ă64 DISK COLLECTION SHOULD GIVE YOU YEARS OF ENJOYMENT! ×HAT MAKES ĐACK ŇAT 64 WORK? ĚIBERAL USE OF MACHINE LANGUAGE IN THE PROGRAM'S DATA STATEMENTS KEEP ANALYSIS TIME REASONABLE. ÔHE ACTUAL ROUTINE THAT ANALYZES EACH SECTOR IS TUCKED INSIDE A SMALL DATA BUFFER IN THE DISK DRIVE. ŮOUR DISK DRIVE HAS A SMALL COMPUTER OF ITS OWN, BUILT-IN, WITH ŇÁÍ, ŇĎÍ, AND A MICROPROCESSOR SIMILAR TO THE Ă-64'S. ŮOUR ĂOMMODORE'S ÄĎÓ (ÄISK ĎPERATING ÓYSTEM) INCLUDES A ÖALIDATE COMMAND TO FIX THE BLOCKS FREE. ÖALIDATE WORKS FINE FOR NON-DAMAGED, NON-PROTECTED DISKS. ÂUT IT WASN'T MADE FOR USE WITH PROTECTED DISKS. ÉF YOU USE IT TO FIX A PROTECTED DISK, YOU RISK LOSING VITAL, HIDDEN INFORMATION THE PROTECTION SCHEME NEEDS TO WORK PROPERLY. ÖALIDATE ASSUMES ALL BLOCKS ARE EMPTY OF INFORMATION UNLESS THEY BELONG TO A PROGRAM OR FILE LISTED IN THE DIRECTORY. ČIDDEN INFORMATION, OFF BY ITSELF -- THE NATURE OF ANY PROTECTION -- WILL BE MARKED AS A FREE BLOCK, TO BE REUSED THE NEXT TIME YOU SAVE INFORMATION TO THAT DISK. ĐACK ŇAT 64 IMPROVES ON THIS BY LOOKING AT EACH BLOCK OR SECTOR, TO SEE IF IT CONTAINS A READ ERROR. ÉF IT DOES, ĐACK ŇAT 64 MARKS THAT BLOCK AS USED, OR "NOT FREE" IN THE ÂÁÍ (ÂLOCK ÁLLOCATION ÍAP). ÔHE ÂÁÍ IS A SPECIAL PLACE ON EACH DISK, WHERE EACH SECTOR HAS A ONE-BIT CODE TO MARK WHETHER OR NOT IT IS FREE. ŇEAD ERRORS ARE ALWAYS MARKED AS "USED" WHETHER OR NOT THEY ARE PART OF A COPY-PROTECTION SCHEME. ĐACK ŇAT 64 CHECKS EACH BLOCK'S INFORMATION AGAINST A PATTERN THAT'S PRESENT ONLY IF THE BLOCK WAS FORMATTED, BUT NEVER USED. ÁNY VARIATION FROM THIS FORMAT-ONLY CODING, EVEN ONE BYTE, WILL TELL ĐACK ŇAT 64 THAT INFORMATION OF SOME KIND EXISTS THERE. ÉF THE SECTOR CONTAINED DATA BESIDES FORMAT INFORMATION, IT IS AUTOMATICALLY MARKED AS USED. ĎTHERWISE, IT IS MARKED AS A FREE BLOCK. ÔHIS INSURES THAT NO INFORMATION IS ACCIDENTALLY OVERWRITTEN, WHEN YOU SAVE OTHER PROGRAMS TO THAT DISK. ĎNLY TRULY EMPTY BLOCKS WILL BE MARKED AS SUCH, WHICH IS WHY THE DISK IS THEN SAFE FOR MORE DATA. ÔHE PROGRAM ITSELF CONTAINS A FEW TRICKS. ĆOR INSTANCE, IT CHECKS THAT YOUR DISK'S WRITE-PROTECT NOTCH IS UNCOVERED, SO IT CAN WRITE TO THE DISK AT THE END. ÔHAT PREVENTS HAVING TO WAIT THROUGH ITS ANALYSIS, JUST TO FIND IT CAN'T CORRECT THE DISK. ÂY PUTTING THE SPEED-IMPORTANT ROUTINES IN THE DISK DRIVE, WHERE THE INFORMATION IS, ALL THE TIME THAT WOULD NORMALLY BE SPENT READING EACH BLOCK'S INFO INTO YOUR COMPUTER IS ELIMINATED. ÔHIS IS WHY THE ENTIRE DISK CAN BE ANALYZED AND CORRECTED IN A REASONABLE TIME, EVEN THOUGH MOST OF THE PROGRAM IS WRITTEN IN ÂASIC 2.0.