cdc_6500_survival_guide
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Both sides previous revisionPrevious revisionNext revision | Previous revisionNext revisionBoth sides next revision | ||
cdc_6500_survival_guide [2021/03/15 23:20] – [File System] hc9 | cdc_6500_survival_guide [2021/03/15 23:28] – [File System] hc9 | ||
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* **Permanent files** | * **Permanent files** | ||
* Permanent files are preserved by the system from their creation until their deletion by user command. Each permanent file is owned by a single user and is normally accessible only by its owner, though it is possible to make files accessible by other users as well. | * Permanent files are preserved by the system from their creation until their deletion by user command. Each permanent file is owned by a single user and is normally accessible only by its owner, though it is possible to make files accessible by other users as well. | ||
+ | * Two types of files are supported: | ||
- | | + | |
+ | * Used for random access and database applications. | ||
- | | + | |
- | * Used for random | + | * Common sequential |
- | | + | |
- | * Common sequential | + | * Whenever an indirect |
+ | * A temporary file is //not// created when a //direct access// file is opened. Changes made to a direct access file are immediately applied to the permanent file. | ||
- | * **Temporary files** Whenever an indirect access | + | * **Primary file** |
- | * A temporary file is //not// created when a // | + | * The primary |
+ | * The currently selected primary | ||
- | * **Primary file** The primary file is the temporary file, usually a program source file, that a user is viewing, modifying, or executing at a given time. Although a user session may simultaneously open multiple temporary files, a given user may have only one primary file at a time. | + | * **Local files** |
- | + | * Local files are the set of temporary files and direct access files (permanent files) currently open by a particular job or user session. | |
- | * The currently selected primary file automatically determines the user's active subsystem. When a new indirect access file is saved as a permanent file for the first time, the file system records the active subsystem at the time. Then when the file is selected as primary sometime later, the system automatically activates the original subsystem. | + | |
- | + | ||
- | * **Local files** Local files are the set of temporary files and direct access files (permanent files) currently open by a particular job or user session. | + | |
File names my be up to seven alphanumeric (upper-case) characters and may not begin with a numeric character. The following file names are reserved by the system: | File names my be up to seven alphanumeric (upper-case) characters and may not begin with a numeric character. The following file names are reserved by the system: |
cdc_6500_survival_guide.txt · Last modified: 2022/12/05 06:33 by hc9