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brabelyesterday at 9:56 AM1 replyview on HN

> the directory at the end is really just for quick access.

No, its purpose was to allow multi floppy disks archives. You would insert the last disk, then the other ones, one by one…


Replies

st_goliathyesterday at 12:00 PM

That literally is quick access, it does the same thing in both cases, trying to get rid of the linear scan and having to plow through data unnecessarily.

If the archive is on a hard disk, the program reads the directory at the end and then seeks to the local header, rather than doing a linear scan. Or the floppy motor, if it is a small archive on a single floppy.

If you have multiple floppies, you insert the last one, the program reads the header and then tells you what floppy to insert, rather than having to go through them one by one, which you know, would be slower.

In one case, a hard disk arm, or the floppy motor, does the seeking, in the other case, your hands do the seeking. But it's still the same algorithm, doing the same thing, for the same reason.