so could be deployed as multiuser systems. Concurrent CP/M-86 3.1 (BDOS 3.1) shipped on 21 February 1984. Adaptations Concurrent CP/M-86 with Windows In February 1984 Digital Research also offered a version of Concurrent CP/M-86 with windowing capabilities named Concurrent CP/M with Windows for the IBM Personal Computer and Personal Computer XT. Concurrent CP/M-86/80 This was an adaptation of Concurrent CP/M-86 for the LSI-M4, LSI Octopus and CAL PC computers. These machines had both 16-bit and 8-bit processors, because in the early days of 16-bit personal computing, 8-bit software was more available and often ran faster than the corresponding 16-bit software. Concurrent CP/M-86/80 allowed users to run both CP/M (8-bit) and CP/M-86 (16-bit) applications. When a command was entered, the operating system ran the corresponding application on either the 8-bit or the 16-bit processor, depending on whether the executable file had a .COM or .CMD extension. It emulated a CP/M environment for 8-bit programs by translating CP/M system calls into CP/M-86 system calls, which were then executed by the 16-bit processor. Concurrent DOS In August 1983, Bruce Skidmore, Raymond D. Pedrizetti, Dave Brown and Gordon Edmonds teamed up to create PC-MODE, an optional module for Concurrent CP/M-86 3.1 (with BDOS 3.1) to provide basic compatibility with PC DOS 1.1 (and MS-DOS 1.1). This was shown publicly at COMDEX in December 1983 and shipped in March 1984 as Concurrent DOS 3.1 (a.k.a. CDOS with BDOS 3.1) to hardware vendors. Simple DOS applications, which did not directly access the screen or other hardware, could be run. For example, although a console program such as PKZIP worked perfectly and offered more facilities than the CP/M-native ARC archiver, applications which performed screen manipulations, such as the WordStar word processor for DOS, would not, and native Concurrent CP/M (or CP/M-86) versions were required. While Concurrent DOS 3.1 up to 4.1 had been developed in the US, OEM adaptations and localizations were carried out by DR Europe's OEM Support Group in Newbury, UK, since 1983. Digital Research positioned Concurrent DOS 4.1 with GEM as alternative for IBM's TopView in 1985. Concurrent PC DOS Concurrent DOS 3.2 (with BDOS 3.2) in 1984 was compatible with applications for CP/M-86 1.x, Concurrent CP/M-86 3.x and PC DOS 2.0. It was available for many different hardware platforms. The version with an IBM PC compatible BIOS/XIOS was named Concurrent PC DOS 3.2. Kathryn Strutynski was the product manager for Concurrent PC DOS.