Where are programs and data stored? - The Tao of Computing - page 92

2. The chapter noted that when storing a file on a disk, a direc
tory contains an entry that indicates both the starting point of
the file (track and sector) and the file's length. Also, corre
sponding to each sector for the file, the computer stores the
location of the next sector. When reaching the last sector for
the file, there is no next sector, so suppose that the computer
records instead that this is the last sector. Discuss how this
arrangement allows the computer to check that files may be
stored using a correct structure.
3. Some utilities perform a series of checks to help determine if
the directories and files are structured correctly. Identify a
few (at least two) tests that such utilities might perform.
4. According to the chapter, RAM is an example of transitory
main memory. Is ROM an example of transitory main
memory or permanent main memory? Briefly explain your
answer.
5. Suppose that a power malfunction occurs at exactly the time
that a file is being saved, thereby preventing some or all ele
ments of a file from being saved correctly. Explain how each
of the following circumstances might arise.
a. The first part of a file has been saved correctly, but the sec
ond half contains junk (nothing related to what was in the
original file).
b. Two files start differently, as they are supposed to, but they
are identical after a certain point; that is, they refer to iden
tical sectors after their initial differences.
c. A file repeats itself over and over, after a certain point.
d. The file has disappeared completely.
6. Explain why defragmenting a disk can improve a computer's
performance considerably, but defragmenting the disk a sec
ond time—immediately after the first defragmentation—has
no further effect.
7. Suppose you open an attachment in an email message.
Nothing seems to happen for awhile, but then a peculiar pic
ture appears on your computer screen. Some time later, you
learn that one of your friends received a message from you
with an attachment having the same effect.