DR Concurrent DOS 386 1.0 (BDOS 5.0?, 1987) DR Concurrent DOS 386 1.1 (BDOS 5.2?, September 1987) DR Concurrent DOS 386 2.0 (BDOS 6.0, 1987-11-18), 2.01 DR Concurrent DOS 386 3.0 (BDOS 6.2, December 1988, January 1989), 3.01 (1989-05-19), 3.02 (1989) Concurrent PC DOS XM 5.0 emulated IBM PC DOS 2.10, whereas Concurrent DOS XM 6.0 and Concurrent DOS 386 2.0 were compatible with IBM PC DOS 3.30. Adaptations Known CCI Concurrent DOS adaptations by Concurrent Controls, Inc. include: CCI Concurrent DOS 386 1.12 (BDOS 5.0?, October 1987) CCI Concurrent DOS 386 2.01 (BDOS 6.0?, May 1988) CCI Concurrent DOS 386 3.01 (BDOS 6.2?, March 1989) CCI Concurrent DOS 386 3.02 (April 1990) CCI Concurrent DOS 386 3.03 (March 1991) CCI Concurrent DOS 386 3.04 (July 1991) aka "CCI Concurrent DOS 4.0" CCI Concurrent DOS 3.05 R1 (1992-02), R2 (1992), R3+R4 (1992), R5+R6 (1992), R7+R8 (1993), R9+R10 (1993), R11 (August 1993) CCI Concurrent DOS 3.06 R1 (December 1993), R2+R3 (1994), R4+R5+R6 (1994), R7 (July 1994) CCI Concurrent DOS 3.07 R1 (March 1995), R2 (1995), R3 (1996), R4 (1996), R5 (1997), R6 (1997), R7 (June 1998) CCI Concurrent DOS 3.08 CCI Concurrent DOS 3.10 R1 (2003-10-05) Other adaptations include: Apricot Concurrent DOS 386 2.01 (1987) for Apricot Quad Version Level 4.3 Multiuser DOS Later versions of Concurrent DOS 386 incorporated some of the enhanced functionality of DR's later single-user PC DOS clone DR DOS 5.0, after which the product was given the more explanatory name "Multiuser DOS" (a.k.a. MDOS), starting with version 5.0 (with BDOS 6.5) in 1991. Multiuser DOS suffered from several technical limitations that restricted its ability to compete with LANs based on PC DOS. It required its own special device drivers for much common hardware, as PC DOS drivers were not multiuser or multi-tasking aware. Driver installation was more complex than the simple PC DOS method of copying the files onto the boot disk and modifying CONFIG.SYS appropriately it was necessary to relink the Multiuser DOS kernel (known as a nucleus) using the SYSGEN command. Multiuser DOS was also unable to use many common PC DOS additions such as network stacks, and it was limited in its ability to support later developments in the PC-compatible world, such as graphics adaptors, sound cards, CD-ROM drives and mice. Although many of these were soon rectified for example, graphical terminals were developed, allowing users to use CGA, EGA and VGA software