Files - Access 2 Learn

Files present a way to store persistent data (that is data that doesn’t go away when a computer is either intentionally, or unintentionally, turned off). Older systems relied on tape, then magnetic disks, and now solid state media.

A file system is used by the OS to manager and track the files on the media.

A file is a named collection of information managed on secondary storage by the file system. Information about the file is stored in a record. This includes things like where the file starts, etc.

Every file consist of data and metadata. Metadata is data about the data, which can give info about when a file was created, what type of file it is, and much more.

The magic number is a short sequence of characters at the start of the file header, which identifies the file type. The type, determines which programs are allowed to access and interpret the file. In DOS and Windows, the file extension serves the same purpose.

A file extension is a weak form of a magic number because it can be arbitrarily changed without actually changing the file type. However, since it’s not hidden, it is easier for the user to see the file type and didn’t take up that meta data space.

Files was originally found on Access 2 Learn

Walter Wimberly

Assistant Professor

Walter Wimberly is an Assistant Professor at a regional college in Tennessee, teaching Computer Science in the Software Engineering track. He works as a student advisor, oversees curriculum changes, develops new courses, and manages the advisory panel.
Walter taught full time for about 7 years, before going back into “industry” as a full stack Software Developer for a dozen years. There he focused on web based projects coding in JavaScript/jQuery and utilizing the Bootstrap CSS Framework on the front-end, and coding in PHP, ASP/ASP.Net, SQL on the back-end.

Since he loves teaching, he taught as an adjunct web and digital media classes for eight (8) years, while working in industry, and has since returned to teaching full time.

He has been married for over 25 years, and is father to several special needs boys. As such, he is working on some projects to help others who have special needs to be self-sufficient, and support the care givers of those with special needs. Check out his Autism blog for more info.

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Security Goals and Threats

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Operating Systems

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Operating Systems

Operations on Files

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Operating Systems

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A reference string is the sequence of page numbers referenced by an executing program during a given time interval. Reference strings are used to compare different page replacement algorithms by counting the number of page faults generated. Since page faults are time consuming, the optimal page replacement algorithm selects the page that will not be referenced for the longest…

Operating Systems

Dynamic Deadlock Avoidance

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Operating Systems

Principles of Scheduling

ByWalter Wimberly September 14, 2020September 14, 2020

Long-term scheduling decides when a process should enter the ready state and start competing for the CPU. It also manages those which are suspended, to acknowledge when they are ready to move to the ready list. Short-term scheduling decides which of the ready processes should run next on the CPU. Most processes move because of the short…

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