Atari Disk And DOS

I own an Atari 800 and a Rana 1000 disk drive. Recently I purchased a game disk. I loaded in DOS, and typed A for a disk directory. All that was printed was how many sectors left. Is there any way to print the names of the files?

T. C. Birgler

At the lowest level of disk access, there are no filenames or directories. Data is stored in 128-byte blocks called sectors. A single-density Atari disk is divided into 720 of these sectors. DOS is a control program that makes this level of the disk invisible to you, and lets you create named files which can be accessed through a directory.

Most game disks don't need DOS, since there is no need for reading or creating named files. These boot disks load directly from the sectors into your computer memory without needing to load DOS. (DOS itself starts to load directly from a boot sector.) Since there are no named files, and no directory on most game disks, there is nothing for DOS to list when it looks on the disk where it expects to find the directory.

All this is similar to the fact that you can't use BASIC to LIST a machine language program. BASIC insulates you from machine language just as DOS insulates you from a disk system that inherently works only with sectors. You can use a disassembler to decode and list machine language. Likewise, there are programs that can directly read and display sector data. But just as you can't make much sense of a disassembly without any knowledge of machine language, the sector data can also be hard to follow without some background on how the disk drive and DOS work.