Editing DR-DOS (section)

==={{anchor|3.31|3.32|3.33|3.34|3.35|3.40|3.41|EZ|ROS}}First DR&nbsp;DOS version===
As requested by several [[Original equipment manufacturer|OEM]]s, Digital Research started a plan to develop a new DOS operating system addressing the defects left by MS-DOS in 1987.<ref name="Caldera_1996_Suit"/> Of particular importance was a million dollar deal with [[Kazuhiko Nishi|Kazuhiko "Kay" Nishi]] of [[ASCII Corporation]], who had previously been instrumental in opening the Japanese OEM market for Microsoft.<ref name="Wein_2009_DOSPLUS"/> The first DR&nbsp;DOS version was released on May 28, 1988.<ref name="Caldera_1996_Suit"/> Version numbers were chosen to reflect features relative to MS-DOS; the first version promoted to the public was DR&nbsp;DOS 3.31,<ref name="Caldera_1996_Suit"/> which offered features comparable to [[Compaq MS-DOS 3.31]] with large disk support ([[FAT16B]] a.k.a. "BIGDOS"). DR&nbsp;DOS 3.31 reported itself as "IBM PC&nbsp;DOS 3.31", while the internal BDOS ([[Basic Disk Operating System]]) kernel version was reported as 6.0, single-user nature, reflecting its origin as derivative of [[Concurrent DOS 6.0]] with the multitasking and multiuser capabilities as well as CP/M [[Application programming interface|API]] support stripped out and the [[XIOS]] replaced by an IBM-compatible [[DOS-BIOS]]. The system files were named [[DRBIOS.SYS]] (for the DOS-BIOS) and [[DRBDOS.SYS]] (for the BDOS kernel), the disk OEM label used was "DIGITAL␠".

DR&nbsp;DOS offered some extended command line tools with command line help, verbose error messages, sophisticated [[command history|command line history]] and editing ([[HISTORY (CONFIG.SYS directive)|HISTORY]] directive) as well as support for file and directory passwords built right into the kernel.<ref name="Brown-Strutynski-Wharton_1983"/> It was also cheaper to license than MS-DOS, and was ROMable right from the start. The ROMed version of DR&nbsp;DOS was also named ROS (ROM Operating System).<ref name="Infoword_1988"/> DRI was approached by a number of PC manufacturers who were interested in a third-party DOS, which prompted several updates to the system.

At this time, MS-DOS was only available to OEMs bundled with hardware. Consequently, DR&nbsp;DOS achieved some immediate success when it became possible for consumers to buy it through normal [[retail]] channels beginning with version 3.4x.<!-- This is known to have happened with either 3.40 or 3.41. -->

Known versions are DR&nbsp;DOS 3.31 (BDOS 6.0, June 1988, OEM only), 3.32 (BDOS 6.0, August 17, 1988, OEM only), 3.33 (BDOS 6.0, September 1, 1988, OEM only), 3.34 (BDOS 6.0, OEM only), 3.35 (BDOS 6.0, October 21, 1988, OEM only), 3.40 (BDOS 6.0, January 25, 1989), 3.41 (BDOS 6.3, June 1989, OEM and retail). Like MS-DOS, most of them were produced in several variants for different hardware. While most OEMs kept the DR&nbsp;DOS name designation, 2001&nbsp;Sales, Inc. marketed it under the name EZ-DOS 3.41 (also known as EZ-DOS 4.1).<ref name="2001Sales_1989"/><ref name="Paul_2002_OS"/>

{{further|Comparison of DOS operating systems}}