Apple IIe - Manual (Page 25)

Page 25 of 74 IIe
Printed: Tuesday, March 4, 2003 10:40:15 AM
When you're using application programs, you're working with two kinds of disks: program disks
and data disks.
The program disk is the disk that contains the application program and the operating system.
If you're lucky, it came with a manual that tells you how to use it, and with a backup copy of
the program disk in case something happens to the original.
A data disk starts out as a blank disk that you buy by the box full from your Apple dealer. It
becomes a data disk when you format it and start saving your data on it.
Formatting
Formatting a disk is a process that marks the disk off (magnetically) into sections where your
data can be stored.
These sections are numbered during the formatting process so the operating
system will have a way of knowing where a particular file has been stored. Once a file is
stored, its location is recorded in the disk's directory (or catalog) along with its name.
Think of formatting as laying down a network of roads on your blank disk. When information is
stored on one of those roads, its address is recorded in the disk's equivalent of an address
book.
When the operating system needs to find a particular file, it checks the address book
and learns that COMPANY.REPORT is located at the corner of 5th and Main. You get the idea.
You need to format a disk only once. If you format a disk that has data on it, that data will
be plowed under and paved over in the process of laying out roads on the disk. Reformatting
disks is a good way to recycle disks that contain data you don't need anymore, but it's a
disaster if you do need the data that was stored on those disks.
Reformatting a disk with
important data is one of those little disasters that happens at least once to everyone who's
ever used a computer.
It's the reason you make backup copies of every data disk.
Many application programs offer formatting as one of the options on the program's menu.
If your application program doesn't give you a way to format disks and if your application
program uses the ProDOS operating system
you can use the formatting program on the ProDOS
User's Disk that came with your disk drive. The ProDOS User's Manual explains how to format
disks.
Formatting Disks for the Right Operating System
It all sounds pretty straightforward. There's only one potential pitfall. There are three
different Apple IIe operating systems:
ProDOS Short for Professional Disk Operating System
DOS 3.3 Short for Disk Operating System, version 3.3
Pascal An operating system designed for programs written in the Pascal programming language.
And each operating system has a different way of formatting disks. If you format a disk for
ProDOS and the program you're using has the DOS 3.3 operating system, it won't know how to
store information on or retrieve information from that disk.
You won't run into this problem if your program disk has a formatting option on the menu. But
some programmers don't give you a way to format data disks on the program disk. (Either they
ran out of space on the program disk or they didn't think it was necessary.) They expect you
to use the formatting program on something called a utilities disk.