Backing up Large Files to Multiple Floppies

Over the last few years the size of files on computers have increased by a significant amount and hard disk sizes have increased similarly. Not so the humble floppy drive which still has a 2Mb unformatted capacity or 1.38Mb (1,457,664 bytes) formatted capacity. This means that more and more of your data files are getting too big to back up to a floppy. There was a floppy drive with double this capacity but it never became very popular and even if you were to locate such a drive and find a motherboard that will support it, finding media with that capacity will be just about impossible.

Compression software can partly solve this problem by reducing the size of the backup copy of the file. Software such as Winzip can typically compress text files to less than half of their original size. With graphics files it depends on the format that you use as to whether a compression program will help as some graphics formats have compression built in and files in these formats will not be able to be reduced further in size by compression programs - particularly ones that use the same algorithm for compression as is already built into the graphics format.

Eventually however we reach the stage where even a compressed copy of a file is too big to fit on a single floppy.

There are larger media drives available such as zip drives and cd (and dvd) writers. If you are making the copy of the file(s) for backup purposes and have one of these drives available then using that drive becomes the obvious solution. It doesn't solve the problem though if you don't have such a drive or you are making the copy of the file to transfer it to a different computer that doesn't have the capacity to read whatever larger media you have available to you. In this case the only practical option is to copy the file to multiple floppy disks.

"But how can I do that", you ask (or why are you bothering to read this page in the first place).

Believe it or not Winzip offers the solution here as well. Instead of creating the zip file backup of your file and then copying it to your floppy, first create an empty zip file on the floppy disk itself. Now all you have to do is to add the file to the zip file that is already on the floppy. Don't worry that the file wont fit because when Winzip runs out of space on the first floppy it will automatically ask you to insert additional floppies one at a time until it finishes adding the file to the zip archive. This is what is called a spanned zip archive because it spans several floppies. Note that you will need to make sure that you have sufficient formatted disks available as it will be awkward to arrange to format them in the middle of creating the zip file and Winzip wont format them for you.

You can create a spanned archive that contains multiple files by just continuing to add files to the open zip archive however if your files are actually too big to fit on individual disks I recommend that you create separate spanned archives for each file as there is a slight risk of a zip archive being corrupted (floppy media isn't perfect) and it is quicker and easier to recreate an archive containing one large file than one containing several.

You can't copy a zip file that already exists and is too big to fit on a floppy onto one directly because it just wont fit and you can't copy the file from within Winzip itself. If you have a zip archive that you want to copy onto floppies and it wont fit onto just one then the only way to do it without unzipping the archive and recreating it on the floppy is to treat the zip archive itself as the large file that you want to copy onto the floppy and create a new zip archive on the floppy to add the original zip file into. As the file is already compressed, adding it into a zip file wont save any extra space (and may actually make the final file fractionally larger) but it will allow you to create the spanned archive that you require.

To copy a spanned zip archive back onto a computer you again need to open the zip archive located on the first floppy. You can then extract the contents of the archive to your hard disk and Winzip will automatically ask for you to insert the additional floppies as it needs them.

So now all you need to do in order to save large files to floppy disk is to get a copy of WinZip.

One final note. You need to be extra careful when you create a spanned zip file to make sure that you keep all of the floppy disks together in a safe place. What you have effectively created is one large compressed file that is stored across a number of separate floppies. Any damage to any of the disks or the misplacing of any of the disks will make the entire zip file completely useless. You might be able to copy all of the parts of the file that are on floppies that you do have and which are not corrupted back to your hard drive but these individual files are not valid zip files by themselves and so can't be opened with winzip and because they are compressed, the data will not make much sense if you open it in any other program. There may be a program that can recover some of your files from the zip archive in this instance but I am not aware of any program with this ability. You have been warned. That said, a spanned zip archive is still a useful way of transferring large files (or lots of small files) between systems where alternative methods are not available.

Why are they called floppy disks? Well the rigid plastic and metal object that people call a floppy disk is actually a caddy and the floppy disk is actually a round and very floppy piece of plastic contained inside. You can see a glimpse of an actual floppy disk by sliding back the metal plate on the caddy. If you have a floppy disk that is no longer useable then you can see for yourself just how floppy the disk actually is by breaking open the caddy and taking the disk out (don't try this with a floppy you want to use as once the caddy is broken the floppy cannot be used within a computer ever again.

The current 3-1/2 inch floppies were originally called microfloppies to distinguish them from their larger relative the minifloppy (which was 5-1/4 inches) and the original floppy (which was 8 inches). Both of these larger relatives had much smaller capacities and came in a flexible plastic case without a cover to slide over the exposed area of the disk.


This article written by Stephen Chapman, Felgall Pty Ltd.

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