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5.4.5 LOGICAL RECORD LENGTH - This field contains the Logical Record Length (LRL) specified when the file was initially generated (via @INIT) or subsequently changed by being overwritten with some file that has another LRL via "COPY (CLONE)" or "BACKUP". A value of "0" indicates that the LRL is equal to 256. 5.4.6 FILE NAME - This field contains the name portion of the file specification. The file name will be left justified and padded with trailing blanks. The name will always be in upper case characters . If a file has FXDE records in addition to the FPDE, only the FPDE will contain the filename in this field. 5.4.7 FILE EXTENSION - This field contains the extension portion of the file specification. As in the name field, it is left justified and padded with trailing blanks. If a file has FXDE records in addition to the FPDE, only the FPDE will contain the file extension in this field. 5.4.8 OWNER PASSWORD - This field contains the hash code of the OWNER password. The OWNER password is used to gain full access to a password protected file. Passwords are assigned at file creation and/or changed with the ATTRIB library command. The 16-bit hash code for a file password can be obtained using the method shown for obtaining the disk master password hash code. 5.4.9 USER PASSWORD - This field contains the hash code of the USER password. THE USER password is required to access the file at the level of protection identified in the attribute field. Passwords are assigned at file creation and/or changed with the ATTRIB library command. The 16-bit hash code for a file password can be obtained using the method shown for obtaining the disk master password hash code. 5.4.10 ENDING RECORD NUMBER - This field contains the ending record number (ERN) which is based on full sectors. If the ERN is zero, it indicates a file where no writing has taken place (or a lot of writing whereby you forgot to close the file). If the LRL is not 256, the ERN value represents the sector where the EOF occurs. Each time a sector is written to the disk, the ERN is advanced by one - even if the sector is not a full sector. Thus, if ERN shows 3, and EOF OFFSET shows 0, then three full sectors have been written (relative 0, 1, and 2). If ERN shows 3 and EOF OFFSET shows 62, then two full sectors and one partial sector of 62 bytes have been written. 5.4.11 EXTENT DATA FIELDS - The extent data fields contain data on the allocation of disk space for the file. Each field is composed of 16-bits and can contain the allocation information for a maximum of 32 contiguous granules. Their contents tell you what cylinder stores the first granule of the extent, what is the relative number of that granule, and how many contiguous granules are in use in the extent. Each extent is encoded according to the pattern illustrated for extent field 1. 5.4.11.1 Extent Field 1 - Bits 15-8 Contain the cylinder number for the starting granule of that extent. The extent uses space on the disk starting from this cylinder and the sector based on the starting granule, for as many granules as are noted in bits 4- 0. Bits 7-5 Contain the relative granule number (0-7) in the cylinder which is the first granule of the file for that extent. This value is numbered starting from zero. (i.e. a "0" indicates that the first granule in use is the first granule on the cylinder. This would be sector 0. A "1" would indicate that 5-12
the first granule in use is the second granule on the cylinder. If there are 6 sectors per granule, sector 6 would start the extent. A "2" would indicate that the first granule in use is the third on the cylinder. If there are 6 sectors per granule, then the first sector in use would be sector 12.) Bits 4-0 Contain the quantity of contiguous granules in the extent. The value is relative to 0. Therefore a "0" value implies one granule, "1" implies two, and so forth. Since the field is 5 bits, it contains a maximum of X'1F' or 31, which would represent 32 contiguous granules. 5.4.11.2 Extent Field 2 - Structured the same as 1. 5.4.11.3 Extent Field 3 - Structured the same as 1. 5.4.11.4 Extent Field 4 - Structured the same as 1. 5.4.12 FXDE LINK FLAG - This field is a flag noting whether or not a link exists to an extended directory record. If no further directory records are linked, the byte will contain X'FF'. If the value is X'FE', a link is recorded to an extended directory entry. 5.4.13 FXDE LINK POINTER - This is the forward link to the extended directory noted by the FXDE LINK FLAG. The link pointer is the Directory Entry Code (DEC) of the extended directory record. The FXDE will then contain the Directory Entry Code of this directory entry in the FLAG field and the month sub-field of the DATE field. This other DEC becomes the backward link. Figure 5-8 represents one directory entry record illustrating a file with two extents. ============================================================================= | | | |- ATTRIBUTES [active directory entry record] | | | |- FLAGS [Modified and not backed up] | | | | |- DATE of last modification [July 15, 1983] | | | | | |- EOF OFFSET [position to PUT next byte = 189] | | | | | | |- LRL [256] | | | | | | | |- Name [HITINFO] | | | | | | | | |- Extension [SCR] | | -- ----- -- -- ----------------------- -------- | | 10 47 7B BD 00 48 49 54 49 4E 46 4F 20 53 43 52 | | 96 42 96 42 25 00 1D 46 23 40 FF FF FF FF FF FF | | ----- ----- ----- ----- ----- ----- ----- ----- | | | | | | | | | |- FXDE link [no FXDE] | | | | | | | | |- Extent 4 [unused] | | | | | | | |- Extent 3 [unused] | | | | | | |- Extent 2 [starts cyl 35, gran 2, 1 gran] | | | | | |- Extent 1 [starts cyl 29, gran 2, 7 grans] | | | | |- ERN [ 37 sectors written ] | | | |- User PASSWORD [blanks] | | |- Owner PASSWORD [blanks] | | | ============================================================================= Figure 5-8: Illustration of a directory record entry 5-13
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MISOSYS, INC. The Programmer's Guid
Page 3 and 4:
1. Introduction Many thousands of u
Page 5 and 6: language (i.e. BASIC, C, PASCAL, ..
Page 7 and 8: NAME START END DESCRIPTION LOWCORE
Page 9 and 10: ackup utility provides exceptional
Page 11 and 12: 3. Device Input/Output Interfacing
Page 13 and 14: 3.2.2 VECTOR Field - This field in
Page 15 and 16: FILTER *PR USING *S0 the operating
Page 17 and 18: ===================================
Page 19 and 20: ===================================
Page 21 and 22: ENTRY JR BEGIN ;Branch around linka
Page 23 and 24: DATA1 EQU $-DATA$ DB 0 ;Data storag
Page 25 and 26: Offset Contents +0 Contains the las
Page 27 and 28: image of the serial port UART statu
Page 29 and 30: called TRACKs. Each track is then d
Page 31 and 32: The DCT contains the information re
Page 33 and 34: accessed a single-sided diskette, t
Page 35 and 36: containing the disk's directory. Th
Page 37 and 38: Command Purpose RESTORE Recalibrate
Page 39 and 40: available from Logical Systems, Inc
Page 41 and 42: exceeds this capacity, then it must
Page 43 and 44: is two physical cylinders. Although
Page 45 and 46: 5. The DOS Directory Structure 5.1
Page 47 and 48: ===================================
Page 49 and 50: 5.2.8 PACK NAME - This field conta
Page 51 and 52: The position of a file's hash code
Page 53 and 54: 5.4 THE DIRECTORY RECORD STRUCTURE
Page 55: Bit 3 Specifies the visibility; if
Page 59 and 60: travels the turnpike. In this manne
Page 61 and 62: The @FSPEC SVC will transfer the fi
Page 63 and 64: A high level language permits you t
Page 65 and 66: does exist, @RENAME should return e
Page 67 and 68: Next, it would be very useful if th
Page 69 and 70: LD HL,FCBX+9 ;Point to the LRL fiel
Page 71 and 72: operating system for such a purpose
Page 73 and 74: position where the last character i
Page 75 and 76: ecord. If a file has more than four
Page 77 and 78: DE Contains a pointer to the File C
Page 79 and 80: @RENAM SVC-56 Rename a file on disk
Page 81 and 82: @FNAME SVC-80 Obtain filespec given
Page 83 and 84: @WRSEC SVC-53 Write a disk sector @
Page 85 and 86: 7.6 SUPERVISOR CALL DETAILS 7.6.1 @
Page 87 and 88: Note: @EXIT in SYS1 automatically r
Page 89 and 90: 7.6.10 @CLOSE SVC-60 This SVC will
Page 91 and 92: 7.6.18 @DCSTAT SVC-40 This SVC pass
Page 93 and 94: Directory to Buffer Entry: B 1; Fun
Page 95 and 96: 7.6.31 @FLAGS$ SVC-101 This SVC wil
Page 97 and 98: NFLAG$ This "network" flag is used
Page 99 and 100: 7.6.32 @FNAME SVC-80 This SVC will
Page 101 and 102: 7.6.40 @HEX8 SVC-98 This SVC will c
Page 103 and 104: 7.6.48 @KLTSK SVC-32 This SVC will
Page 105 and 106: 7.6.57 @OPEN SVC-59 This SVC will o
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Registers Affected: AF, BC. Entry:
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0-14 FILENAME/EXT:D - left justifie
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7.6.71 @REMOV SVC-57 This SVC will
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Entry: DE A pointer to the FCB cont
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Exit: A Error return code, if any.
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CURSOR CHARACTER Registers Affected
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Exit: A Will contain the error code
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esident routine into its execution
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CKPAWS LD A,@FLAGS$ ;Get Flags poin
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===================================
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The TYPE=0A indicates that it is th
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Error 08: Device not available A re
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Error 28: End of file encountered T
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8.5 HEADER PROTOCOL OF MEMORY MODUL
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This is obviously an extremely usel
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LD (IX+2),15 JR TASKA By firmly und
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8.7.3 Details of Low Memory Page 2
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actual bank switching. As previousl
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set. Thus, the Z-flag will be indic
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8.10 SYSTEM DISK BOOT TRACK The ope
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14 DEBUG 72 PURGE 1B VERIFY 71 DUMP
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8.13 USING @PARAM The @PARAM SuperV
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DW LPARM+1 DB 'FEED ' ;Line feed pa
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;*=*=* PPARM LD BC,0 ;Zero because
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8.14 TRAP Filter Illustrated ;TRAP/
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8.15 SLASH0 Filter Illustrated ;SLA
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8.16 DMP-500 BOLDFACE Filter Illust
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NOMEM$ DB 'High memory is not avail
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@ @ABORT..........7-2, 7-4, 7-8, 7-
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