|This article's lead section may not adequately summarize key points of its contents. (September 2016)|
|Original author(s)||Watcom, Sybase,
|Initial release||January 8, 2003|
1.9 / June 2, 2010
2.0 / April 2, 2015
|Written in||C, C++|
|Size||66 to 84 MB|
|Type||Integrated development environment|
|License||Sybase Open Watcom Public License version 1.0 (free usage for noncomm usage)|
Though no longer sold commercially by Sybase, the Watcom C/C++ compiler and the Watcom Fortran compiler have been made available free of charge – for non commercial usage, as the Open Watcom package.
The Open Watcom C/C++ version 1.4 release on December 2005 introduced Linux x86 as an experimental target, supported from NT or OS/2 host platforms. There is code for an abandoned QNX version, but libraries necessary for it to be compiled could not be released as open source.
Stable version 1.9 was released in June 2010.
A forked version 2.0 beta was released that supports 64-bit hosts (Windows and Linux), built-in text editor, 2-phase build system, and the DOS version supports long filenames (LFN).
The Open Watcom Wiki has a comprehensive history.
|1984||Waterloo C for S/370|
|1985||Work on current code generator codebase started|
|1988||Watcom C 6.0||
|1989||Watcom C 7.0|
|1989||Watcom C 7.0/386|
|1990||Watcom C 8.0|
|1990||Watcom C 8.0/386|
|1991||Watcom C 8.5|
|1991||Watcom C 8.5/386|
|1992||Watcom C 9.0|
|1992||Watcom C 9.0/386||
|Watcom C 9.01/386||
|1993||Watcom C/C++ 9.5|
|1993||Watcom C/C++ 9.5/386|
|1994||Watcom C/C++ 10.0|
|1995||Watcom C/C++ 10.5|
|1996||Watcom C/C++ 10.6|
|1997||Watcom C/C++ 11.0|
|1998||Watcom C/C++ 11.0B|
|1999||Sybase issues end-of-life notice for Watcom C/C++ 11.0|
|2000||Sybase announces open sourcing of Watcom tools|
|2001-09-27||Watcom C/C++ 11.0c Beta|
|2002-12-21||Watcom C/C++ 11.0c|
|2003-01-28||Open Watcom 1.0|
|2003-08-12||Open Watcom 1.1|
|2004-01-07||Open Watcom 1.2|
|2004-08-03||Open Watcom 1.3|
|2005-12-14||Open Watcom 1.4|
|2006-04-26||Open Watcom 1.5|
|2006-12-15||Open Watcom 1.6|
|2007-08-18||Open Watcom 1.7|
|2007-10-23||Open Watcom 1.7a|
|2009-02-21||Open Watcom 1.8|
|2010-06-02||Open Watcom 1.9||Current Official Version|
|2015-04-02||Open Watcom 2.0 Beta||GitHub V2 Fork. Open Watcom ported to 64-bit hosts (Window and Linux), Resource compiler and Resource editor support WIN64 executables, built-in text editor, 2-phase build system, DOS version of tools support long filenames (LFN), numerous fixes.|
The Open Source Initiative has approved the license as open source, but Debian, Fedora and the Free Software Foundation have rejected it because "It requires you to publish the source code publicly whenever you “Deploy” the covered software, and “Deploy” is defined to include many kinds of private use."
The compiler can be operated from, and generate executable code for, the DOS (MS-DOS, FreeDOS), OS/2, Windows, Linux operating systems. It also supports NLM targets for Novell NetWare. There is ongoing work to extend the targeting to Linux and modern BSD (e.g., FreeBSD) operating systems, running on x86, PowerPC, and other processors.
In the mid-1990s some of the most technically ambitious MS-DOS computer games such as Doom, Descent, Duke Nukem 3D, and Rise of the Triad were built using Watcom C/C++, some such as ROTT using the DOS/4GW protected mode extender with the Watcom compiler.
Open Watcom's syntax supports many conventions introduced by other compilers, such as Microsoft's and Borland's, including differing conventions regarding (for instance) the number of leading underscores on the "asm" tag. Code written specifically for another compiler rather than standard-compliant C or C++ will often compile with the Watcom compiler.
The compiler supports C89/C90 standards by default.
Open Watcom supports partial compatibility with the C99 standard. It implements the most commonly used parts of the standard. However, they are enabled only through the undocumented command-line switch "-za99". Three C99 features have been bundled as C90 Extension since pre-v1.0: C++ style comments (//), flexible array members, trailing comma allowed in enum declaration.
The compiler currently doesn't support any new major C11 features, though the C library does include "Safe C" functions. It is specified in ISO/IEC TR 24731-1 and known as "Bounds-checking interfaces (Annex K)" in C11. Some function name examples are strcpy_s(), memcpy_s(), printf_s(). This library was released along with Open Watcom 1.5 in April 2006.
- "Latest Release (June 2010) - Open Watcom". OpenWatcom.org wiki.
- List of main differences of v1.9 to v2.0 Beta.
- History - Open Watcom. OpenWatcom.com wiki.
- Free Software Foundation. "Various Licenses and Comments about Them". GNU Operating System. Retrieved Dec 23, 2014.
- Installing Open Watcom on Linux - Open Watcom. OpenWatcom.org wiki.
-  "RotT was written in Watcom C++ v10.0 with the Rational Systems DOS/4GW extender."
- "How 5 years of burning ambition brought Retro City Rampage to DOS". Gamasutra.
- "Open Watcom V2 Fork".
- "Open Watcom V2 Fork Project on GitHub".
- "pcdosasm.zip archive". 2010-07-27. Retrieved 2014-02-10.
Modified Open Watcom C/C++ DOS 16-bit ..\STARTUP\DOS\CSTRT086.ASM code
- "C99 compliance in Open Watcom". Archived from the original on May 3, 2015. Retrieved 25 September 2015.
- ISO/IEC TR 24731-1; Extension to the C Library, Part 1: Bounds-checking interfaces.
- WG14 N1969 — "Updated Field Experience With Annex K — Bounds Checking Interfaces", Carlos O'Donell, Martin Sebor
- Open Watcom Safer C Library
- Open Watcom, official website, (Archived March 17, 2015, at the Wayback Machine.)
- Open Watcom V1.9 binary downloads
- Open Watcom V2 Fork on GitHub
- Open Watcom V2 Fork binary downloads
- Paul Hsieh. (May 8, 2005). "The WATCOM C/C++ Programmer's FAQ". Retrieved Oct 7, 2008.
- Rick Grehan (October 1994). "Watcom C/C++ Gets a New Face". BYTE. 19 (10): 111. Archived from the original on 1997-07-12. Retrieved 2011-05-14.