While earlier Apple II Disk Operating Systems (DOS) were based on DOS 3.3, the latest version of a DOS for the Apple II is called ProDOS. Disks formatted with ProDOS are easy to identify.

A data disk when booted (or started for those wondering what the word booted means), that's formatted with ProDOS, will load up with a screen that may say something like: Data Disk, Not Startup Disk

or: *** Unable To Load ProDOS ***

A self-booting ProDOS disk when started, will start up with a screen identifying which version of ProDOS is loaded on the disk, so you know for sure that your disk has been formatted with ProDOS.

There are a number of differences between Apple's early DOS 3.3 & ProDOS, which are too technical for the scope of this article, but one of the most important differences between the two operating systems is that ProDOS can use subdirectories (sort of like a folder within the main directory of the disk).

Another big difference between DOS 3.3 & ProDOS is the size of the operating system. Whereas DOS 3.3 resides on the first 2 tracks of the disk, ProDOS is a program stored within the main directory of the disk & takes up considerably more room, primarily because of it being a much more complex operating system. ProDOS also stores data on it's disks in blocks as opposed to sectors under DOS 3.3

However, probably the main difference between them is the fact that you cannot format a disk under ProDOS without a separate formatting utility such as that found on the ProDOS System Master disk or within programs such as Copy II Plus (a disk utility), Appleworks or many other ProDOS based programs.

To format a disk for ProDOS, you must first load your formatting utility, then select the option which says Format A Disk or Initialize A Disk. Oncce you have selected this option, you must select the drive you wish to format the disk in. If you only have one disk drive, then you must be sure to remove the disk your formatting utility & replace it with your blank disk as formatting a disk completely erases any information that may be on the disk. You will also be asked to enter a name for the disk you want to format. Call it something simple, like Test or Data.

Once the formatting has been completed, you must then copy a couple of files to the disk so as you can use it, unless you only wish to use the blank disk for data. To do this, you must use the disk utility you used to format the disk, either the ProDOS System Master Disk or a utility such as Copy II Plus.

Select the Copy Files option from the menu of your chosen utility & then specify the drive you wish to copy from & the drive you wish to copy to. Don't make the mistake of mixing up the drives or you may copy over information on the disk which contains your copying utility. For this reason, it's a good idea to Write Protect your disk.

Write Protecting prevents you from overwriting any information on a disk. To write protect a 5.25" disk, you should use one of the Write Protection tabs that usually come on the label sheet in the box with your disks. Simply stick half the label on one side of the disk so as it completely covers the notch (hold the front of the disk so as the exposed disk material is facing towards the lower edge of the disk - the label is usually the top of the disk - the notch should now be on your right) in the side of the disk. The simply fold the write protection tab over to cover the notch on the rear side of the disk.

To write protect a 3.5" disk, all you need to do is hold the label side of the disk facing away from you & the metal shield away from you & pointing towards the lower edge of the disk. The write protect tab on these disks is built in, assuming you are holding the disk correctly, the write protect notch should be on your upper left. If you can see through the notch, the disk is write protected. If you can only see plastic, then you need to use something sharp, like a small fingernail & push the piece of plastic upwards until you can see through the disk - this means it is now write protected.

Back to the task at hand though & you should now have selected the drive you wish to copy to & from. Once this is done, you should be presented with a list of files on the source (the disk you want to copy from) disk. Select the files PRODOS.SYSTEM & BASIC.SYSTEM & then select copy. Follow any prompts that come onto the screen. Once this process has finished, you have a disk ready to start up.

Put your new disk into the startup drive & then either hold down OPEN APPLE-CONTROL & then hit RESET to start the machine or switch the computer off the back on. The disk should start up & you'll be put straight into Applesoft BASIC. Congratulations! You now have a startup disk.

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