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BOOT CAMP 040
FILING FOR FUN, PART 2
In last week's Boot Camp we looked at some of the ways files
can be transferred from one PC to another. In part two we're focusing on the
types of files you're most likely to send or receive, and how to squeeze a digital
quart into a pint pot.
Files are identified by a three (sometimes four) letter or
number code -- called an 'extension' --
that comes after the full-stop following the file name. There are literally hundreds
of different types but don't worry, most of them you'll never see or have to
worry about as they are only used by Windows and the programs on your computer.
Unless you're a heavy-duty PC user, or running exotic applications you will
probably only ever encounter a dozen or so different file types. However, if
you do comes across something unusual on your machine and you want to find out
what it is, or what the extension means there's a handy utility in Windows
Explorer and My Computer. It's on the View Menu, under Folder Options, click on
the File Types tab and you'll find details of all the file formats your machine
is currently using.
Since word processing is the single most popular application
for most PCs the files you're most likely to want to transfer to another
machine will contain text. There are two distinct types of text file, for
documents and plain text. Document files are created by your word processor, they
contain generic formatting information, such as character attributes -- typeface and size, bold and italic
letters etc., and layout styles. MS Word and WordPerfect document files have
the extension .doc, Lotus WordPro uses .lwp, Word for the Mac uses .mcw, and so
on. In general these documents are meant to be read by the word processor
program they're written on, though most WPs can also read documents in an alien
file format but some style information may be lost. However, the big problem
with generic WP file formats is that they take up a lot of space.
If you want to transfer a large amount of text from one PC to
another, on disc, via a network or over the Internet (as e-mail) it is more
convenient, and usually a lot quicker, to send it as a plain text ASCII file (see
Jargon Filter). Text files have a .txt extension and contain just the words plus
simple style and layout information. Plain text files can be read on any word
processor but most importantly, they are quite small. For example, a 1000 word Word
97 document requires at least 32 kilobytes of disc space; the same 1000 words occupies
only 8kb or so as plain text. That makes a big difference to the time it takes
to send a document by e-mail, or the number of documents a floppy disc will
hold. There's also the possibility that the recipient of a formatted WP
document may not have the same program on their computer and will be unable to
read it. By the way, most newspaper, magazine and book editors prefer to
receive submitted copy as plain text (whether on disc or by e-mail) as it can
be easily imported into page layout and DTP programs where it will be adapted
to their house style.
Next, pictures and graphics files. They make up one of the
largest families of file formats but again there is a degree of common currency
that allows images to be easily swapped between computers. The standard Windows
picture file format is the bitmap, with the extension .bmp. Bitmap files can be
very large indeed; a small colour picture can easily swallow up several
megabytes of disc space. Bitmaps are often too large to get on a floppy disc,
and sending a bitmap file over the Internet takes forever. The alternative is
to compress the data, by discarding unnecessary information and picture details
the eye cannot see. The most widely used compression scheme is JPEG (extension
.jpg), which can reduce file sizes by factors of 10 to 100 times without
significant loss of quality, moreover JPEG files can be displayed on a very
wide range of paint box and graphics programs. Pictures on Internet web pages
are usually JPEG files; simple graphics (buttons, icons, logos, backgrounds
etc) are normally sent as compressed GIF files (Graphics Interchange Format), with
the file extension .gif.
When it comes to moving very large or complicated lumps of
software around between computers a more precise means of reducing file size is
needed. Data can be reliably compressed using a variety of techniques; the best
known is 'Zipping'. Files with the
extension .zip are widely used for downloading information and programs from
the Internet. Some compressed files are self-extracting. Once the file is on
the PC hard disc (and checked for viruses) double-clicking the file icon
automatically opens and installs the file or program. However most compressed
files rely on the PC having its own extraction utility program, such as WinZip
or PKZip. Clicking on a zipped file automatically starts the extraction
program. Shareware versions are freely available as from the web sites we’ve
listed. No Internet PC should be without one of them! These programs also allow
you to create your own compressed files, packing very large amounts of text or
data onto floppy discs, or for sending over the Internet.
You might also come across a coding scheme called Uudeview,
which creates files with the extension .uue. This file format is used to
convert information -- pictures, programs etc. -- into plain text characters,
so they can be sent over the Internet as e-mail. Uudeview coded files look like
huge documents full of gobbledegook text. They can be easily decoded using a
simple Windows program, also available in shareware form from the web site on
the Contacts list.
Next week, working with pictures
CONTACTS
www.winzip.com
www.pkunzip.com
www.miken.com/uud
JARGON FILTER
ASCII
American Standard Code for Information Interchange, text coding
system, recognised by all PCs
DTP
Desktop publishing -- makeup and layout programs used to
design pages in printed documents, magazines, newspapers and books
JPEG
Joint Photographic Experts Group -- part of International
Standards Organisations, responsible for devising software compression systems.
Picture file format used for storing photographs, data is compressed thus
saving space and reducing download times on Internet pages
TOP TIP
If you need to quickly make a copy of a floppy disk -- maybe
a colleague needs to see some files you've been working on -- then Windows 95
and 98 can help. From your desktop or the Start Button open My Computer then right-click
on the floppy disc icon and select Copy Disk on the menu. Windows then reads
the entire contents of the disc into the PCs memory; a bargraph shows how the
copy process is progressing. When the indicator reaches halfway Copy Disc will ask
you to remove the original disc and load a blank formatted floppy. Make there's
nothing on it or it may be overwritten, click OK and the information is read
back to the second disc.
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