But wait: Remember that the disk controller doesn’t fill up every possible
cluster with data. The computer uses its own form of shorthand for effi-
ciency in retrieving information; if the capacity of a cluster is 512 KB and
a particular file is 514 KB in length, the controller is going to use two clus-
ters, one of which will hold only a pair of lonely kilobytes of information.
And then we have to deal with disk drive fragmentation. If you begin
work on a chapter of a book, it may well start in one cluster and con-
tinue to the next; but when you come back to make edits, the file may be
broken up into lots of little chunks scattered around the disk because
that is where the available space exists. The result of fragmentation is
first of all a slowing in the retrieval speed of data, and secondly an
increase in wasted clusters. (Chapter 2 tells you how to defrag your
computer.)Just to add to the confusing math of hard drive capacity, consider the fact that
many laptop manufacturers set up a hidden partition on the hard drive that
comes with the system to hold compressed copies of much or all of the original
operating system and utilities. They do this for your own protection — it’s a
convenient way to quickly restore your machine to its as-delivered configura-
tion (although you will lose all data and any applications you have added on
your own.) This hidden partition may eat up a few more gigabytes of space.So, what’s the bottom line? It’s almost impossible to say with any precision.
The first thing to do is to determine how the maker of your hard drive or
computer defines capacity: Are they using the technical specs, where 1 giga-
byte is equal to 1,073,741,824 bytes? Or are they using a marketer’s 1 gigabyte
of 1,000,000,000 bytes? And then reduce the number by 15 percent to sub-
tract overhead. And then take out another 10–15 percent for various and
sundry waste. In my personal shorthand, a 10GB drive is good for about 7GB
of data, whether it is a designer gigabyte or a marketer’s gigabyte. The brand-
spanking-new “60GB” drive on a new laptop I purchased while working on
this book actually netted a bit more than 53 real gigabytes of storage before
I went to work on it to remove some of the supplied software and special
offers that were of no use to me.What’s to retain here? More is better. If you have a choice between a 30GB
and a 40GB hard drive in your new laptop and it makes economic sense to do
so, go for the 40GB device — it’ll give you, oh, 7GB more storage.How fast is fast? ..................................................................................
In most uses of a laptop the microprocessor, memory, and LCD screen cannot
operate any faster than the flow of information they receive from the hard
drive (or a CD or DVD drive). In a modern machine, in most situations it is a120 Part III: Laying Hands on the Major Parts