Atari DOS

Atari DOS, briefly for Atari - disk operating system (too German: Of disks operating system), one developed exclusively for the use on ATARI-8-Bit-Computern.

ATARI Diskettenformate with 90kB and later also 130kB storage location were supported. Disks were described on one side and read.


the most well-known versions are DOS II 2.0s of 1980 and 2.5 of 1984. Between them there was also still another DOS 3,0, which at first with the new 130kB-Diskettenlaufwerk “ATARI was delivered 1050”. DOS 3,0 was not accepted however because of compatibility lacking and large storage location speicherplatzverschwendung by the customer. Thus the DOS 2,5, which DOS resembled 2,0 much, developed however the 130kB-Unterstützung offered.

structure and characteristics

ATARI DOS consisted in the reason of two files:

DOS.SYS offered functionality for the creation, renaming, deletion and reading from files as well as a formatting of disks. These functions could of programs over the D: - Dealers (see below) to be called.

DUP.SYS offered a menu controlled Shell, which made direct working possible with DOS for the user. Additional functions, which DOS.SYS did not contain, were copying as well as duplicating files.

When the Atari 130XE came on the market, still RAM disk was added - driver (RAMDISK.COM), which made the additional 64 KB available of the computer as floppy disk drive.

Files knew after from the PC range admitted 8,3 - convention to be designated, i.e. 8 indications of the file name and additional 3 indication of the extension, separately by one point. All letters were converted into capital letters. Starting from DOS 2,5 the first indication could be in the name also a number. In the table of contents of a ATARI disk the representation was changed. Genutze indications of the actual name were not filled up with blanks and the point before the file extension was not represented. Sublists to put on was not possible. The maximum number of files on a disk was limited to 64, however for lack of storage location was hardly reached.

In order to be able to use a ATARI with a floppy disk drive, the ATARI DOS had to be loaded with boats. Without ATARI-8-Bit-Computer did not offer diskette functionality to boats of a diskette operating system. Several DOS versions for the ATARI could be developed by this circumstance, not on ATARI DOS were based. Thus DOS versions, those, suitable hardware developed presupposed, for data media with up to 16 MT to administer could and the functionality of sublists and even time stamps offered.

The size of files and/or. the free storage location was indicated in sectors. With the density of writing used by the ATARI DOS a sector was large exactly 128 byte (later DOS versions used a high memory density of 256 byte per sector). The latter 3 byte of a sector formed sector left. It gave information over the number of data bytes belonged in this sector (usually 125), the file number and the number of the next sector to this file. The exact size of a file in bytes could not be gotten to know directly.

Under DOS 3,0 4 sectors were combined into a block. That made with large files a storage location saving of 9 bytes per block (were there only the blocks linked), however took small files at least one block, thus 4 sectors and/or. 512 bytes (under DOS 2 only 128 bytes) on the data medium.

the D: - Dealers

ATARI disks become over the so-called D: - Dealers addressed. The ATARI OS offered further dealers, like e.g. K: (Key board/keyboard), S: (Screen/Bildschrim), E: (Editor/screen and keyboard). These dealers in the ATARI OS are comparable with today's hardware drivers. The D: - Dealer was loaded with DOS. Thus DOS instructions without the menu guidance “DUP.SYS” could be implemented (strictly speaking one could omit the DUP.SYS, if one wanted to provide a boatable disk and make as much as possible storage location available). To rename one knew a file e.g. with the instruction

XIO 32, #1,0,0, “D: old name, new name”

a resuming enumerating would blow up the framework here. To the ATARI naturally also several floppy disk drives could be attached to be over exact up to 8. These became then with D1: to D8: responded.


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