APPENDIX G. LET/FLET

The Location Equivalence Table (LET) contains the name and disk block count of all programs and data files stored in the User Area, including the System Library. The Fixed Location Equivalence Table (FLET) contains the names of all programs and data files stored in the Fixed Area.

Each cartridge must have a LET. FLET is optionally defined on each cartridge by the DUP control record DEFINE FIXED AREA.

LET/FLET DISK FORMAT

All entries are three words long and consist of a name and disk block count. In addition, each sector of LET/FLET contains a five word sector header.

LET/FLET Entries

Entries	DSF (LET only)	CI	Data
Word 1, bits 0-1	00	10	11
Word 1, bits 2-15 plus Word 2	Program or data file name in name code
Word 3	DB count of program or data file

Sometimes unused disk space occurs because programs and data files are stored on sector boundaries.

Such spaces are represented by a 1DUMY entry:

Word 1, bits 0-1	Reserved
Word 1, bits 2-15 plus Word 2	Name code for 1DUMY
Word 3	DB count of entry

The last entry of LET is a 1DUMY entry reflecting the current size of WS available.

LET/FLET Sector Header

Word	Entry
1	Relative sector number for this cartridge only
2	Sector address of the UA (sector address of FX if FLET)
3	Reserved
4	Number of words available in this LET/FLET sector.
5	Sector address for the next LET/FLET sector of this cartridge. This entry is zero if this is the last LET/FLET sector on this cartridge.

LET/FLET DUMP FORMAT

The DUP control records DUMPLET or DUMPFLET are used to dump LET/FLET on the principal printer. One sector of LET/FLET is printed per page. The page is headed with the word LET or FLET, whichever is applicable. Each sector of LET/FLET dumped is preceded by two lines of header information. The first header line contains the contents of the following locations from COMMA/DCOM:

#CIDN -- Cartridge ID, Logical Drive 0, 1, 2, 3, or 4
$FPAD -- COMMA File Protect Address, Logical Drive 0, 1, 2, 3, or 4
#FPAD -- DCOM File Protect Address, Logical Drive 0, 1, 2, 3, or 4
#CIBA -- CIB Address, Logical Drive 0, 1, 2, 3, or 4
#ULET -- LET Address, Logical Drive 0, 1, 2, 3, or 4
#FLET -- FLET Address, Logical Drive 0, 1, 2, 3, or 4

Following this line will be a second header line which reflects information concerning the LET/FLET sector being dumped:

Relative Sector Number (SCTR NO.)
User Area/Fixed Area (UA/FXA)
Word Available (WORDS AVAIL)
Chain Address (CHAIN ADR)

Following these two header lines are the LET/FLET entries. Twenty one lines of entries are printed, five entries per line and sequenced by column. Each entry is formatted as follows:

Name -- 5 print positions + blank
Type code -- DSF, DCI, or DDF -- 3 print positions + blank, 4 blanks if 1DUMY or secondary entry point
DB Count -- 4 print positions + blank
DB Addr -- 4 print positions + 5 blanks

Only the name is printed for each secondary entry.

Examples of DUMPLET and DUMPFLET follow.

LET/FLET page 125

LET/FLET page 126

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