Editing Atari DOS (section)

==Disk formats==
A number of different formats existed for Atari disks.<ref name=":0" /> Atari DOS 2.0S, single-sided, single-density disk had 720 sectors divided into 40 [[Track (disk drive)|tracks]]. After [[Disk formatting|formatting]], 707 sectors were free. Each 128-byte sector used the last 3 bytes for [[Housekeeping (computing)|housekeeping]] data (bytes used, file number, next sector), leaving 125 bytes for data. This meant each disk held 707 × 125 = 88,375 bytes of user data.

The single-density disk holding a mere 88 KB [[floppy disk|per side]] remained the most popular Atari 8-bit disk format throughout the series' lifetime, and almost all commercial software continued to be sold in that format (or variants of it modified for [[copy protection]]), since it was compatible with all Atari-made disk drives.

* ''Single-Sided, Single-Density'': 40 tracks with 18 sectors per track, 128 bytes per sector. 720 sectors, 90 KB capacity.
* ''Single-Sided, Enhanced-Density'': 40 tracks with 26 sectors per track, 128 bytes per sector. 1040 sectors, 130 KB capacity. Readable by the 1050 and the XF551.
* ''Single-Sided, Double-Density'': 40 tracks with 18 sectors per track, 256 bytes per sector. 720 sectors, 180 KB capacity. Readable by the XF551, the 815, or modified/upgraded 1050.
* ''Double-Sided, Double-Density'': 80 tracks (40 tracks per side) with 18 sectors per track, 256 bytes per sector. 1440 sectors (720 sectors per side), 360 KB capacity. Readable by the XF551 only.

===Percom standard===
In 1978, [[Percom]] established a double-density layout standard which all other manufacturers of Atari-compatible disk drives such as [[Indus GT|Indus]], [[Amdek]], and Rana —except Atari itself— followed. A configuration block of 12 bytes defines the disk layout.<ref name=":1" /><ref name="wilkinson198510">{{cite news | url=https://archive.org/stream/1985-10-compute-magazine/Compute_Issue_065_1985_Oct#page/n111/mode/2up | title=Atari Disk Drive Compatibility | work=Compute! | date=October 1985 | access-date=16 October 2013 | author=Wilkinson, Bill | pages=110–111}}</ref><ref>{{Citation |last=Kay Savetz |title=Charles Marslett, MYDOS and FastChip — interview |date=2020-08-16 |url=https://archive.org/details/charles-marslett |access-date=2024-09-14}}</ref>

=== RAMCART ===
It is ramdisk for Atari XL, compatible with many DOS software.<ref>{{Citation |last=Janz |first=Holger |title=HolgerJanz/RAMCART |date=2024-05-27 |url=https://github.com/HolgerJanz/RAMCART |access-date=2024-09-14}}</ref>

=== IDE Plus 2.0 ===
It is a utility to work with Atari disks and diskettes, based on MyDOS and SpartaDOS.<ref name=":2" />