DOS XL – a Disk Operating System created by Paul Laughton, Mark Rose, Bill Wilkinson, and Mike Peters and published by Optimized Systems Software (OSS) for the Atari 8-bit family of home computers.
DOS was originally produced by OSS as a development of OS/A+, then passed to ICD, where, however, more emphasis was placed on developing SpartaDOS. Some improvements to DOS XL were made later by FTe.
The authors of DOS XL are Paul Laughton, Mark Rose, Bill Wilkinson and Mike Peters.
DOS XL first appeared in version 2.20 (version 2.10 was still called OS/A+), then 2.30, finally a revised edition of the latter known as DOS XL 2.30P. Versions for the Apple II were planned (hence the inscription ATARI version visible in the picture), but they were never released.
Special versions of DOS XL were included with the floppy drive:
– DOS XL 2.35I1 with Synchromesh support for Indus GT
– DOS XL 2.35I2 with SuperSynchromesh support for Indus GT with RAM Charger extension.
– DOS XL 2.35I1 in two additional editions: for LDW Super 2000 and CA-2001 stations (with appropriately changed station name in system programs and different Synchromesh procedure for CA)
The DOS XL 2.35L version mentioned in the LDW Super 2000 and CA-2001 manual does not actually exist.
There were plans to release version 4.x as a development of OS/A+ v.4.1, but they were abandoned due to little market interest. It is possible, however, that DOS XL 4.x finally appeared a few years later in a modified form as DOS XE. This cannot be said with 100% certainty, but two facts may indicate it:
– the author of DOS XE is OSS programmer Bill Wilkinson;
– the DOS XE floppy disk format shares some peculiarities with the OS/A+ v.4.1 format
The DOS XL screenshot source: Wikipedia, author: Optimized Systems Software, License: Public Domain.