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45 lines
1.6 KiB
Plaintext
45 lines
1.6 KiB
Plaintext
; ARCHIVE FORMAT
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; FIRST BLOCK LOOKS ALMOST EXACTLY LIKE A DISK DIRECTORY EXCEPT FOR
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; THE FIRST FOUR WORDS:
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; WORD 0 - ALWAYS -1 TO DISTINGUISH FROM OLD ARCHIVES
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; WORD 1 - "UDNAMP" RELATIVE POINTER WITHIN DIRECTORY TO
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; START OF FIRST NAME AREA BLOCK
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; WORD 2 - "UDESCP" BYTE NUMBER OF NEXT AVAILABLE BYTE IN
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; DESCRIPTOR AREA
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; WORD 3 - GC TAG - SYSTEM PACKED DATE/TIME OF LAST REARRANGEMENT
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; OF DIRECTORY (E.G. DELETION, INSERTION, GARBAGE COLLECTION)
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; ONLY OTHER DIFFERENCE FROM STANDARD DISK DIRECTORY IS IN 5TH WORD
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; OF EACH NAME BLOCK. DISK USES LEFT HALF FOR REFERENCE DATE, DOESN'T
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; USE RIGHT HALF. ARC USES LEFT HALF FOR REFERENCE DATE, USES RIGHT HALF
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; FOR COUNT OF NUMBER OF OPENS FOR READING.
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; SECOND BLOCK:
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; WORD 2000 - ACCESS POINTER TO FIRST BLOCK IN FREE BLOCK CHAIN
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; (0=>CHAIN IS EMPTY)
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; WORD 2001 - NUMBER OF FREE WORDS IN ENTIRE ARCHIVE
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; WORD 2002 - NUMBER OF FREE BLOCKS IN ENTIRE ARCHIVE
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; WORD 2003 - NUMBER OF WORDS IN USE IN ENTIRE ARCHIVE
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; WORD 2004 - NUMBER OF BLOCKS IN USE IN ENTIRE ARCHIVE
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; WORD 2005 - RELATIVE POINTER (RELATIVE TO 2005) TO NEXT AVAILABLE
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; FBAT ENTRY (0=>FBAT IS FULL)
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; WORDS 2006-<2005+200.> - THE FBAT - EACH ENTRY POINTS TO
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; THE FIRST DATA BLOCK IN A FILE.
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; WORDS <2005+200.>-EOF - DATA BLOCKS
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; A DATA BLOCK:
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; HEADER - 4.9 BIT - 1=>BLOCK IS FREE
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; 4.8 BIT - 1=>LAST BLOCK IN FILE CHAIN
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; 4.9,4.8 BITS BOTH 1 => SINGLE WORD OF GARBAGE
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; 4.7 BIT - UNUSED
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; 4.6-3.6 - LENGTH-1 OF DATA AREA (NOT INCLUDING HEADER AND TRAILER)
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; 3.4-1.1 - DISK ADDRESS OF NEXT DATA BLOCK IN THE CHAIN
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; TRAILER - IDENTICAL TO HEADER EXCEPT
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; 3.4-1.1 - DISK ADDRESS OF PREVIOUS DATA BLOCK IN THE CHAIN
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