Creating or destroying a file effects the FCB with creation creating the FCB and allocating space for the file is only done when there is contents for the file, which often happens almost instantaneously, while deleting/destroying the file means that its resources are released so another use can use it.
The Open File Table is used to keep track of currently opened files. This allows for easier/faster access to those files because you don’t have to go through the whole list of files.
An open file command checks various things including, permissions, setting up read/write buffers, creating an entry in the open file table, setting up an index to read the file on the storage medium, and more.
The read file operation copies the contents, or at least partial contents, of a file into the main system memory. You may read the whole file (if it is small), or portions.
A write file operation copies data from memory into a file.
The close file operation “undoes” the open file operation, closing out its entry in the open file table and closing the file so it cannot be corrupted.
Operations on Files was originally found on Access 2 Learn
