distinguish between a sequential access, a direct access, and a random access storage device. write one example of each?
Answers
If you happened to be around in the 90s, when the web was invented, you may remember that "hypertext” was the buzzword at the time. In fact, “HTML” itself stands for “Hypertext Markup Language.” Hypertext made the web work as an interconnected media form: text that contains links (hyperlinks) to additional content that can be immediately accessed.
The hypertext and hyperlink exemplify the direct-access paradigm and are a significant improvement over the more traditional, book-based model of sequential access.
(Direct access can also be called random access, because it allows equally easy and fast access to any randomly selected destination. Somewhat like traveling by a Star Trek transporter instead of driving along the freeway and passing the exits one at a time, which is what you get with sequential access.)
In a normal, physical book, the reader is supposed to read pages one by one, in the order in which they are provided by the author. For most books (fiction, at least), it makes little sense for the reader to turn directly page 256 and start reading there. Unless, of course, that is where the reader left off in their last reading session. Getting to page 256 in a 500-pages book poses a bit of a challenge, as we well know it, and each of us have their preferred method of dealing with it (be it a bookmark, a dog ear, or our own memory).
Tables of contents try to alleviate a book’s sequential-access problem by telling people what content is going to be found in the book and at which page. The user still has the problem of turning to the desired page number, but at least he doesn’t need to bother with parsing the content and deciding whether he’s found what he is looking for.
By definition, however, the web embraces direct access. Thus, it is disappointing to see sequential-access designs becoming increasingly popular nowadays.
Direct access allows the access of an element directly by locating it by its index number or address. Ex: CD.