Upgrading & Fixing Laptops DUMmIES

wedge near the hole but have many more spaces at the outside of the circle.

(There’s also something called a cluster,which is a group of sectors linked

together.) Okay, you’re almost at the end of your excursion into metaphor,

analogy, and simile. You’ve seen how the circular disk/arena can be subdi-

vided into an indexed chart of memory locations/seats through the use of

tracks/rows and sectors/sections.

But for the computer, it is very important that it have a quick, logical, and

easily managed scheme to remember what information has been placed where,

as well as to know what space is available for new recording. It does this by

thinking in terms of those wedge-shaped sectors; when the computer wants

to store a page of text, a snippet of sound, or a piece of an image, it finds an

empty sector and starts recording from the beginning of that sector to the end.

If the data fills up the entire sector, that’s just peachy; however, if the sector

has the capacity for 512 bytes but the information consists of just 64 bytes,

three-quarters of the sector is going to be left empty and unused. That’s just

the way it is; the system trades wasted space for speed and simplicity.

Therein lies the answer to the burning question: How come I’m only able to

fit (for example) 814K of data on a 1.4MB floppy disk? What you’ve got here

is a bunch of short files that result in a lot of wasted space. Generally, sound

and graphic files are large and result in relatively little squandering; text and

data files are shorter and could be more wasteful. It also depends on whether

the disk has been freshly formatted or whether there are bits and pieces of

other files scattered around the disk; floppy disks (and hard drives) become

increasingly fragmented over time, at least until they are cleaned up using a

defragment utility — something I discuss in Chapter 2.

And remember the idea of clusters: A large cluster is more efficient for large

files and extremely inefficient for smaller ones. Not that it really matters to

users, but the computer numbers the tracks from the outside in. The outer-

most track is called 0, and the innermost 79. All of the tracks are squeezed

into a band less than inch wide — 80 tracks at a density of 96 per inch.

Old-Style Physics in a Modern Machine....................................................

The analogies are now finished. Let me talk, briefly, about the mechanical

side of the floppy disk drive. When you insert a floppy into a drive, a little

catch slides back the cover that sits over the Mylar circle within. Once it is

fully in place, the pair of pegs on the motor find their mating holes in the

middle of the disk.

Within the drive, a pair of read/write heads move into position — one above

and one below the disk. In a floppy disk drive, the heads actually touch the

142 Part III: Laying Hands on the Major Parts