Here are a few “techtips” written for a professional association.

By Jeanne Rescigno:

Zippity Doo Dah!

You will often hear of “zip” or “zipped” files. These files are loosely referred to by the name of a pioneer in the category (in the DOS/Windows world, anyway), PK Zip software. Mac users frequently refer to “stuffed” files, after a popular compression program. Today, there are a number of programs available that do the same things: compress and archive files.

Coding and De-coding

Compression software analyzes the file and devises more efficient ways to encode information. It then re-writes the file to make it take less space on a disk. This analysis and re-writing gets down to a very “low” (machine-level) language. Some kinds of files compress better than others; word processing and database files are generally quite successful while other kinds of files may be less so. The extent to which the file can be compressed is a function of a number of factors such as the amount of redundancy in the file and the amount of “blank” space. In addition, there is a direct trade-off between speed and the level of compression.

Archiving means compiling a number of smaller files into a single file. Your Internet Explorer “favorites,” for example, are all individual but tiny files and you may have dozens of them. If you want to give a friend a copy of your favorites or some of them, especially if you wish to e-mail them, it would make sense to archive them into a single unit. It just makes handling them easier on both ends, assuming the recipient can un-archive them.

Embedded in the final “zipped” file is a table and an algorithm which, themselves, take room. Therefore, in a sense, one adds overhead when zipping. When I zipped four Internet Explorer favorites, I ended up with a file larger than the sum of its parts. Of course, this is an unusual scenario (ordinarily you would not bother archiving four favorites), but worth noting.

As you may have surmised already, the recipient of one of these files needs the same software to “read” the manner in which the file was archived and/or compressed and de-code it back into a Word file or an Excel file or a Quark file or whatever. That is, it is quite useless as a zipped file. But it sure handles and downloads more easily.
Avoiding De-coding

Many of these packages will also create a “self-extracting” archive. The program will pack a little code into the file so that it is no longer really a compressed data file; it is now a program that contains its own de-compressing and de-archiving instructions. Much downloaded software is distributed this way; the *.exe file unpacks into its own directory and multiple files (program files and data files). The governing program then executes the additional instructions needed to accomplish the installation. In this scenario, the recipient just needs to click on the file and does not need to own or master any compression or archiving software.

The trade-off is that some folks will resist taking executable code from you because of virus risks while they will happily take a compressed data file and de-code it themselves.

What, Me Worry?

Backing up is one of the most important things you can do on your computer. Yet, in fact, it can mean different things to different people. For good reason.

But it’s all about being prepared for the unexpected. And the unexpected can take many forms. Here are some back-up strategies and the worries they address:

Save from memory to a file on disk: I can hardly imagine a reason not to save work regularly to your hard disk. Whatever is on your screen (in random-access memory, that is) is a phantom, an illusion. It has no permanence whatsoever until you give it a name and record it on your hard drive. Protect yourself from accidental deletions (your new kitten walked across your keyboard?!) or a sudden loss of power (happened to me at 9 p.m. when an electrician thought no one else was left in the office). If you have been working for 20 minutes, call it anything at all and save it anywhere at all, but record it. You can always zap it later. My hard drive is littered with files called “hold”—my default, automatic name for a file that is temporary. When I am on a clean-up mission, I do not even open them, I just delete them. But they were stored for some period of time, just in case.
Save a copy to diskette: If your machine goes down (or does not start!) have your current work on a handy disk. Always, at least once at the end of the day, consider what you would really like to have in the morning and put it on a diskette. That way, you can always take it to another computer. Are you the only one with Word Processor Brand X in the office? (Why? (oh rugged individualist!)) Well, if you possibly can, save your work to plain text or rich text format or something that virtually any program can open.

Save to diskette even on a day when you are doing a bigger back-up. Sometimes, you just need to get at your current work quickly and getting it off of a tape of your entire hard drive is going to take a long time at best. There is no “random access” to a backup tape.
Save to another file name: Protect yourself from inadvertent deletion or overwriting. It is really not hard, at the end of a long day, to accidentally delete (or more commonly, overwrite) a file. In the latter case, typically, you open a file, meaning to give it a new name but, after changing some of it, you accidentally and quite automatically save it to the original name. You have lost the earlier version forever. Get familiar with your file management utilities (e.g., File Manager or Explorer) so that you can copy the file before you ever open it.
Save to multiple file names: On a big project, history can be important, sometimes more important than you can anticipate. Remember that two pages you loved but the boss did not? Well, now he would like them back. (Because the big boss liked them!) Or, harkening back to earlier scenarios, even if you destroy today's work somehow or catch a virus today, you still have the project as of yesterday and will only have to re-create that one day’s work.

At least once a day, save mega project JONES to a new name—jones.001, jones.002, etc. Or use the date: jones201.bak, jones202.bak. An added advantage of altering the extension (the part of the name after the period) is that the file will not open automatically (in the Windows world). You really have to work to open this up and mess up.
Save it to another location: Protect yourself from fire, floods, and theft. If information is important, take a copy home or store it anyplace but in the same office. [Aside: Files are getting bigger all the time, and may not fit on one diskette. But compression software can work wonders with text files. Otherwise, get another storage device, preferably one that is pretty common, like Iomega’s Zip Drive.]
Save to a more distant location: Protect yourself from widespread disaster. The truth is that a back-up in the same city may be vulnerable. It does not happen often, but hurricanes, floods, earthquakes, etc. can make a joke of a back-up across town. Major financial institutions store back-up tapes in caves thousands of miles away. Here is an interesting possibility, available thanks to today’s speedy and ubiquitous telecommunications: zipping your data over telephone lines to be stored.
Save your whole hard drive: There are a number of strategies for this and yours will depend on the size of the drive and the kind of information you have stored. Most back-up software will let you copy everything, or copy only those files that are new since the last back-up, or copy only those files that have changed. The software also does some compression. Most experts advise backing-up your entire hard drive regularly. But remember, if you do periodic back-ups, you are advised to do periodic restores to ensure that everything is working properly. Further, bear in mind that, after a total wipe-out, restoring an entire drive is rarely a simple thing. As a rule, you need to format the drive, install the operating system, install the back-up software (it also does the restore routine) and, possibly, install some hardware drivers. Also beware of obsolete backup equipment and software. Some people worry a lot about taking a snapshot of the entire drive. Others feel that they can always re-install software, but the data are crucial. Some have a lot of software that was downloaded over the years and can not readily be obtained again. In any case, if your drive is big enough to partition, you can easily separate programs and data, making it easier to back-up your own irreplaceable data more often.

Clients & Servers

There are two words you should get familar with for all Internet business, if you have not done so already: client and server. Roughly, a “client” is the user’s software (for example, your E-mail and browser programs are clients). A “server” is the software sending data to the user. The server interprets commands from computers and “serves" you the information you ask for.

In some applications, in fact, the user’s software performs both client and server functions; but that is a highly technical caveat. Another “exception” is that many people can log on to their Internet providers’ machines and use client software there (a shell account) without ever installing it locally. But if you are doing that, you know about it and probably do not need this article at all.

Rule of thumb: If you read or hear “the client,” and have no information to the contrary, you can safely assume the reference is to software on your own machine.

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