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back2root:ibm-pc-ms-dos:hardware:informations:file-system-format [2023/03/03 17:46] – [File Descriptor] frater | back2root:ibm-pc-ms-dos:hardware:informations:file-system-format [2023/03/03 17:52] (Version actuelle) – [Tableau] frater |
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===== DOS 4.0+ System File Table and FCB Table ===== | ===== DOS 4.0+ System File Table and FCB Table ===== |
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| ^ Offset ^ Size ^ Description ^ |
| | 00 | dword | pointer to next system file table; offset of ffffh indicates last table in chain | |
| | 04 | word | number of file descriptors in table | |
| | 06 | nbytes | file descriptor table of the format (59 bytes each): | |
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| ==== File Descriptor Table ==== |
Offset Size Description | {{tablelayout?rowsHeaderSource=Auto}} |
| ^ Offset ^ Size ^ Description ^ |
00 dword pointer to next system file table; offset of ffffh | | 00 | word | count of handles referring to this file or zero if file is no longer open | |
indicates last table in chain | | 02 | word | open mode, bit 15 set if file id opened via FCB | |
04 word number of file descriptors in table | | 04 | byte | file attribute | |
06 nbytes file descriptor table of the format (59 bytes each): | | 05 | word | device info word | |
| | 07 | dword | if char device pointer to device driver header if block device pointer to DOS Device Control Block or REDIR data | |
Offset Size Description | | 0B | word | starting cluster of file | |
| | 0D | word | file time | |
00 word count of handles referring to this file or | | 0F | word | file date | |
zero if file is no longer open | | 11 | dword | file size | |
02 word open mode, bit 15 set if file id opened via FCB | | 15 | dword | current file position | |
04 byte file attribute | | 19 | dword | if network redirector, pointer to REDIRIFS record word if local block dev, relative cluster within file of the last cluster read | |
05 word device info word | | 1B | dword | if local, sector number of directory entry | |
07 dword if char device pointer to device driver header | | 1F | byte | if local, number of directory entry within sector | |
if block device pointer to DOS Device Control Block | | 20 | 11bytes | filename in FCB format | |
or REDIR data | | 2B | dword | SHARE pointer to previous SFT sharing same file | |
0B word starting cluster of file | | 2F | word | SHARE number of network machine opening file | |
0D word file time | | 31 | word | PSP segment of file owner | |
0F word file date | | 33 | word | offset within SHARE code seg of sharing record 0000h = none | |
11 dword file size | | 35 | word | absolute cluster number of last cluster read zero if file has never been read or written | |
15 dword current file position | | 37 | dword | pointer to file IFS driver, NULL if native DOS | |
19 dword if network redirector, pointer to REDIRIFS record | |
word if local block dev, relative cluster within file | |
of the last cluster read | |
1B dword if local, sector number of directory entry | |
1F byte if local, number of directory entry within sector | |
20 11bytes filename in FCB format | |
2B dword SHARE pointer to previous SFT sharing same file | |
2F word SHARE number of network machine opening file | |
31 word PSP segment of file owner | |
33 word offset within SHARE code seg of sharing record | |
0000h = none | |
35 word absolute cluster number of last cluster read | |
zero if file has never been read or written | |
37 dword pointer to file IFS driver, NULL if native DOS | |
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