But what if your disk drive is connected to the computer through the disk drive port and not to a slot? In this case, you supply the slot number that corresponds to the disk drive port. For 3.5-inch drives, the corresponding slot is 5. For 5.25-inch drives, the corresponding slot is 6. (The disk drive port was designed to emulate a slot with a disk drive controller card so you'd be able to use software that looks for a controller card in a slot.)

If you have more than one drive of the same type connected to the disk drive port, drive 1 is the drive connected directly to the computer. Drive 2 is the drive connected to drive 1.

Other applications may expect you to indicate where you want your document saved by typing the document name followed by a comma, followed by the letter D (short for drive) and a drive number. For example, typing MEMO, D2 or .D2/MEMO tells the operating system to save the document named MEMO on the disk in drive 2. If you don't type a D and a drive number, the application assumes you want to save it on the disk in the drive you last accessed.

When you tell your application to save a document on a disk, it hands the job over to a subcontractor called the disk operating system.

The disk operating system is a set of programs on every application program disk that handles the transportation of documents between the memory of the computer and disks. (See Figure 4-3.)

The only reason you need to be aware of the disk operating system is that there are three varieties—ProDOS^®, Pascal, and DOS 3.3—and each variety requires that disks be formatted in a particular way.

If your application uses ProDOS (that is, if the application is ProDOS-based), documents created with that application can be stored only on ProDOS-formatted disks. If your application program is Pascal-based, documents created with that application can be stored only on Pascal-formatted disks.

Figure 4-3
What the disk operating system does

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Chapter 4: Saving Documents