Atari DOS

Atari DOS, short for Atari Disk Operating System, is an operating system for use on Atari 8- bit computers.

Atari disk formats were supported with 90 kB, and later 130 kB of memory. Disks have been written and read unilaterally.

Versions

The best known versions are DOS II 2.0s of 1980 and 2.5 in 1984. Between, was published nor DOS 3.0, which was initially shipped with the new floppy drive ATARI 1050 and first offered support for disks with 130 kB memory capacity. However, it was not accepted because of its high memory requirement and the partially resulting lack of compatibility with older software by the customer. So DOS 2.5 was released, a DOS 2 with support for 130 kB diskettes.

Structure and properties

DOS.SYS offered the functionality for creating, renaming, deleting, and reading files and formatting disks. These functions could of programs via the D: are invoked handler ( see below).

DUP.SYS offered menu-driven access to these functions. Additional features that are not contained DOS.SYS were copying and duplicating files.

When the Atari 130XE came on the market, a RAM disk driver ( RAMDISK.COM ) has been added which provided the additional computer memory as a floppy drive.

Files could be named after the 8.3 convention known from the PC sector, ie eight characters for the filename and three additional characters for the extension, separated by a dot. All letters are converted to uppercase. From DOS 2.5, the first character in the name could also be a digit. In the contents of an Atari floppy disk, this display has been changed. Unused characters of the actual names have been padded with blanks and not shown for the period before the file name extension. To create subdirectories was not possible. There were a maximum of 64 files can be created on a floppy disk, which was quite sufficient for the small storage capacity of the disk.

To use an Atari with a floppy drive, DOS, Atari had to be loaded at boot time. Without booting a floppy disk operating system Atari 8 -bit computers offered no floppy functionality. Due to this fact several DOS versions for the Atari could be developed that were not based on Atari DOS. So DOS versions arose, provided the appropriate hardware, could manage disks with up to 16 MB and offered the functionality of subdirectories and even timestamps.

The size of files and the free space is specified in sectors. In the write density used by Atari DOS sector was exactly 128 bytes ( later versions of DOS used a high storage density of 256 bytes per sector). The last three bytes of a sector formed the sector link. He provided information on the number of data bytes in this sector (usually 125 ), the file number and the number of the next sector belongs to this file. The exact size of a file in bytes could not be brought into direct experience.

Under DOS 3.0 four sectors have been grouped into a block. This made for large files, although a memory space savings of nine bytes per block ( since only the blocks were linked ), but took small files at least one block, four sectors and 512 bytes ( under DOS 2 only 128 bytes ) on disk is a.

Atari disks are the so-called D: addressed handler. The Atari DOS offered another handler, such as K: (keyboard / keyboard ), S: (screen / screen), E: ( Editor / screen and keyboard). These handlers in Atari DOS are comparable with current hardware drivers. The D: handler was loaded with DOS. Thus DOS commands could be executed without the menu DUP.SYS ( DUP.SYS could be omitted if you create a bootable floppy disk and wanted to maximize the amount of space). Rename a file you could, for example, with the command

XIO 32, # 1,0,0, "D: oldname, newname "

On the Atari maximum of eight disk drives could be connected. These were then compared with D1: to D8: addressed.

  • DOS operating system
  • Atari
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