OS/2 2.0 Frequently Asked Questions, Programmer's Edition

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This FAQ is for programming and development-related issues for OS/2 2.0. It is freely distributable.

Answers to questions closer to the bottom of the list may rely on information given in prior answers. Customers outside the United States should not necessarily rely on 800 telephone numbers, part numbers, or upgrade policies contained in this list; all prices are listed in United Stated dollars unless otherwise specified.

Many of the answers below refer to anonymous ftp from FTP-OS2.NMSU.EDU ( The name 'ftp-os2' is used as a shorthand to refer to this machine.

Questions addressed in this release: (a * indicates that no answer is available; all answers are currently incomplete)


Languages, Compilers, Debuggers

What programming languages come with OS/2 2.0?

The original BASIC and BASICA (for systems with BASIC in ROM), DOS's QBASIC, and OS/2's REXX come with OS/2 2.0. See question #1.7 for information on REXX.

What C/C++ development environments are available?

Many companies offer C or C++ compilers. The following list is almost guaranteed to be incomplete and somewhat inaccurate.

IBM Workset/2, 1-800-3-IBM-OS2, $895. Includes the C Set/2 compiler, the IPMD multithreaded PM debugger, the Workframe/2 development environment, and the Developer's Toolkit (utilities and online documentation). These pieces are also available separately. The full product announcement is available on ftp-os2. Bug reports for C Set/2 can be mailed to cset2@vnet.ibm.com, for Workframe/2 to workframe@vnet.ibm.com and will go straight to the developers.

NOTE: Workset/2 was available at a promotional rate of $295 in the US and $399 in Canada, but the originally announced end dates have passed. I do not know if the promotion has been extended, so I assume it has not.

  • Watcom C 9.0, (519) 886-3700.
  • JPI C and C++, (415) 967-3200 (USA), +44 234 267500 (UK/Europe), $180.
  • Glockenspiel C++, (+353)-1-733166.
  • Microway C++, $595.
  • GNU C. Two flavors of the GNU C compiler are available, both on ftp-os2. GCC/2, based on GNU C 2.2.2, is in /pub/os2/2.0/programming/gcc2-2.2.2, and emx/gcc is in /pub/os2/2.0/programming/emx-0.8d. See question #1.3 for information on the differences between the two.

What are the differences between the two available versions of GNU C?

The two versions of GNU C that are available were ported to OS/2 with different goals and philosophies in mind and therefore have different characteristics. However, both systems include a fairly complete C library and can be used to compile useful programs, although their support of Unix-specific semantics differs. Furthermore, both systems are being actively developed and are constantly improving.

The goal of GCC/2 is to create a pure, freely redistributable OS/2 2.0 development environment with no extra baggage for backwards compatibility; it is based on the assumption that DOS will die and is not worth worrying about. It is based on GNU C 2.2.2, supports C and C++, and can create PM programs. It produces "native" 32 bit .OBJ files that are linked with OS/2's LINK386.EXE, and can be linked together with .OBJ files produced by IBM C Set/2 and other compatible compilers. The mailing list os2gcc@charon.mit.edu exists for discussion of this port; send mail to os2gcc-request@charon.mit.edu for subscription information.

emx/gcc 0.8d, also based on GNU C 2.1, supports only C and can create PM programs. (emx/g++ is now available in beta release, and will eventually be added to emx/gcc.) emx's goal is to make porting Unix programs easier by emulating Unix semantics as closely as possible. It produces programs that can run both under OS/2 using EMX.DLL and under DOS using the emx DOS extender. emx/gcc uses standard Unix development tools like ld and nm, and attempts to support Unix-isms like select(). A version of gdb exists that can debug emx/gcc programs. An emx-related mailing list exists; send mail to LISTSERV@ludd.luth.se with a subject of "help" for subscription information. (Note that this is a *NEW* address for the emx discussion list.)

How can I view the GNU C documentation?

GNU C/C++ comes with documentation from the Free Software Foundation in texinfo (.texi) format. This documentation is about gcc in general, and has no OS/2-specific information.

All utilities needed to compile/view/tex the texinfo files are readily available for OS/2. The GNU texinfo package, available on ftp-os2 in pub/os2/all/gnu/gnuinfo.zoo, includes makeinfo.exe for compiling texinfo, info.exe for viewing them, and texinfo.tex and texindex.exe for TeXing them.

An ASCII text version of the gcc documentation is also available on ftp-os2, in the file pub/os2/2.0/gnu/gcc21/gcctxt.zoo.

What other programming languages are available for OS/2? (Esp. inexpensive ones.)

Virtually all of them: Assembler, COBOL, Pascal, Fortran, Smalltalk, Modula-2, LISP, Forth, Perl, and more. The OS/2 Tools Guide on ftp-os2 (pub/os2/all/info/tinf26.zoo) contains information on these and more.

[Vendors, ftp sites, phone numbers, prices?]

Pascal: Microway ($595), JPI ($180)
Modula-2: JPI ($180), Stonybrook
Fortran: Microway ($595), Watcom
Cobol: IBM Cobol/2
Smalltalk: Digital Smalltalk/PM V, Parc Place Smalltalk
Perl 4.0.10: ftp-os2
LISP: ftp-os2
XScheme: ftp-os2
J: ftp-os2

Which of these compilers can be used to generate PM apps?

IBM C Set/2 can generate PM apps. Workset/2 includes many sample programs and the complete on-line reference.

GNU C/C++ 2.1 can generate PM apps, and includes a sample program that does it. emx/gcc can too, with some limitations (what are they?).

Most commercial C and C++ compilers can. WATCOM C and FORTRAN and all of JPI's can, too. You will probably want the IBM Developer's Toolkit, or similar documentation, however.

What is REXX? How do I write and run a REXX program?

REXX is the IBM SAA (Systems Application Architecture) standard, user-friendly programming language. It is available for IBM mainframes, Unix, the Amiga, DOS (Mansfield's Professional REXX), Windows, and many other platforms. It has been a part of standard OS/2 since Version 1.3. Programs written in REXX that do not use system-specific libraries are fully portable.

OS/2 2.0 comes with an online REXX reference, and printed REXX documentation is available (Mike Cowlinshaw's REXX book, IBM's twin guides). The Usenet group comp.lang.rexx discusses REXX programming.

What debuggers are available for OS/2?

IPMD, a PM-based debugger, ships with C Set/2. It is capable of source- and assembly-level debugging multithreaded 16 bit and 32 bit OS/2 applications.

emx comes with gdb, the GNU debugger.

There are also several commercial debuggers on the market. WATCOM C and FORTRAN come with WVIDEO, a full-screen source or assembly level debugger that handles multithreaded 16 and 32 bit OS/2 programs.

Multiscope, others?

Where can I get documentation on the OBJ/LIB/EXE format used by OS/2 2.0?

The .EXE format was described briefly in PC Magazine, Vol 11 No. 12 (June 30, 1992?); it was also described in a 1988 issue.

Please summarize this information, and tell me what I need to do OS/2 development.

GCC/2 crashes with a trap when I try to compile a program. Why?

Because you didn't read the README or INSTALL files, probably. There are three general reasons GCC/2 will crash:

  1. You did not set up the environment variables in CONFIG.SYS properly. Read doc/INSTALL for instructions.
  2. Some program that gcc expects to be in the PATH is not; unfortunately, gcc crashes instead of just printing an error message. You may forgotten to install something, or your PATH may be wrong; see above. Giving gcc the -v option will cause it to print each command line as it executes it; this will tell you which program is missing.
  3. You are trying to get gcc to link your program for you. It cannot because ld does not exist, and so it crashes (see item 2). You must specify -c, -E, or -S on every invocation of gcc, and then use LINK386.EXE to create an executable. See the sample makefiles for an example of how to do this.

Tools, Toolkits, Accessories

What programming editors are available for OS/2?

OS/2 2.0 comes with the Enhanced Editor (EPM).

GNU Emacs 18.58 is available. It requires you to have emx installed on your machine, but it comes with all the emx files you will need. Emacs is available on ftp-os2 in /pub/os2/2.0/gnu/emacs. (If you want to recompile emacs, you will need the full emx distribution; see question 1.2.)

Several public-domain vi clones are available, including elvis, Stevie and levee. The MKS Toolkit also includes vi.

Many other text editors are available.

  • Epsilon, by Luguru, (412) 421-5678. DOS upgrade to OS/2 is $90. This is a character based editor, not a PM app.
  • QEDIT, Brief, KEDIT, others? [Vendors, phone numbers, prices?]

What programming tools/toolkits/accessories are available for OS/2?

The IBM Programmer's Toolkit, included in Workset/2, includes many tools.

Borland will soon release ObjectVision for OS/2. [Details?]

The MKS Toolkit, available from MKS ($349 USD, 800-265-2797 or inquiry@mks.com), has over 160 Unix tools, including Korn shell, tar, vi, awk, grep, tail, cpio, and so forth. It also contains a Lex and Yacc capable of generating C, C++, and Turbo Pascal code.

There is a product called ARGO/UX which provides a BSD environment for OS/2. [details?]

What GNU tools are available and where can I find them?

OS/2 1.x versions of most of the standard GNU utilties are available on various OS/2 ftp sites, and they will work under OS/2 2.0. Either gcc or emx/gcc should be able to compile 2.0-specific versions of any of them; if you port any, please announce it. emx also comes with a collection of utilities that are necessary or useful to use it.

Is a socket library available? How can I use it?

IBM's TCP/IP 1.2.1 ($200, part #02G6968) includes an optional Programmer's Toolkit ($500, part #02G6973). It includes a socket library, and support for Sun RPC, NCS RPC, and a limited Kerberos capability. It requires IBM C Set/2 or another compiler that understands 16-bit code.

FTP Software, Inc., has an OS/2 version of its TCP/TCP product. They can be reached at (617) 246-0900 or info@ftp.com.

Walt Corey, KZ1F, is porting KA9Q to OS/2 and PM. The current version of his code is available for ftp from giskard.uthscsa.edu. This is still a work in progress, with rough edges here and there, and in particular there's no Ethernet (or anything but async serial, i.e. SLIP, PPP, and KISS) support yet, though that's high on the priority list. You can email Walt at kz1f@giskard.uthscsa.edu.

If you have the IBM TCP/IP 1.2 base package and IBM C Set/2, you can use the TCPIPDLL.DLL directly. A 32 bit socket library interface to do this for you will be available shortly. It will also be possible to call TCP/IP functions from programs generated with gcc. (Yes, yes, I know I've been promising this for a while. I apologize for the delay; be patient.)

Programming, Porting

How can I recompile public domain/shareware source code for OS/2?

Most publicly available OS/2 programs come with binaries (since there is currently only one OS/2 architecture). If you are porting source code from another system (for example, Unix), you will first need to acquire a compiler. See section 1 for information on compilers; in particular, note that the GNU C compiler is available.

You should realize that many publicly available programs have already been ported to OS/2. Check the many FTP sites carrying OS/2 programs before you reinvent any wheels (the OS/2 User's FAQ contains information on FTP site).

How can I port my DOS program to OS/2?

How can I port my Windows program to OS/2?

To the first approximation, you don't have to - OS/2 2.0's DOS support is excellent, and your DOS program will probably just work; similarly, OS/2 2.0 supports Windows 3.0 (and soon 3.1) programs. See the OS/2 User's FAQ for details.

IBM Workset/2 includes Mirrors, a toolkit designed to help port Windows applications to OS/2. [Details?]

[But this doesn't answer the question...]

Is OS/2 suitable for real time programs?

How do I write an OS/2 device driver?

There's a book called "Writing OS/2 2.0 Device Drivers in C" from Van Nostrand-Reinhold, see question 4.5. There's also IBM's flood of printed material.

How can I simulate (Unix feature) under OS/2?

(a) fork
(b) fork/exec
(c) select

In general, you can't. select() depends heavily on the fact that all sources and sinks of data originate in the filesystem and are identified by a coherent set of file descriptors; these assumptions are not true under OS/2. For (almost) any particular kind of data source/sink (files, sockets, pipes) you can achieve most of select()'s semantics. A decent solution to this problem requires a C library that maintains its own array of file descriptors and information on each one such that it can dispatch to the appropriate module in response to library calls. The C libraries delivered with gcc and emx/gcc will have such functionality in the (possibly near) future, but don't yet.

(d) job control

How does programming PM compare to programming X?

Many people have said "PM is much cleaner." Until I hear from someone I trust with extensive experience with both (I only know X), however, this FAQ will take no position.

Why doesn't printf() produce output when I expect it to?

For historical reasons, most Unix C libraries' stdio default to using line buffered streams, whereas most DOS and OS/2 C libraries' stdio default to using fully buffered streams. ANSI C species that standard output should be line buffered when connected to an interactive device, but not all libraries are ANSI compliant. You can control the buffering algorithm used for a particular stream with the setvbuf() function.

If you didn't understand that paragraph, read on.

printf() is part of the Standard I/O (stdio) library, which uses buffered streams for file IO. ANSI C specifies three algorithms for deciding when to flush the buffer (i.e. when to print buffered data to the file):

  • not buffered. Data is flushed to the file as soon as possible, usually immediately after being received.
  • line buffered. Data is flushed to the file when a newline is received (and the newline is also flushed).
  • fully buffered. Data is flushed to the file when the buffer is full.

Buffered data is always flushed when the stream is closed or when fflush() is called. Since standard output is flushed when main() exits, all data printed with printf() will appear at that time, if it has not already. However, ANSI C does not require that a stream be flushed when scanf() is called on it. Therefore, if you print to a fully buffered stream and then request input on it, it is likely that the input will be read before the printed data appears.

You can control the buffering algorithm used for a particular stream with the setvbuf() function. For example, the statement setvbuf(stdout, NULL, _IOLBF, BUFSIZ) sets standard output to be line-buffered, which is what most Unix programmers expect. Any decent C reference will cover all of this material.

The gcc 2.1 library will have a line-buffered stdout by default in a future release.

Documentation, Help

Where can I get information on OS/2 APIs and programming?

The IBM Programmer's Toolkit, included in Workset/2, includes a complete on-line syscall reference.

You can order the seventeen volume IBM OS/2 Technical Library (possibly at a discount, see question 1.2) and/or order various volumes individually; the file pub/os2/2.0/info/os2pubs.txt lists all (many?) of the IBM OS/2-related reference manuals, as of May 20, 1992, along with ordering information.

See question 4.5 for information on printed reference books.

Where can I get sample code?

There is a lot of sample code included in the IBM Toolkit, and 4 sample programs (with source) included with C Set/2. GNU C/C++, from ftp-os2, includes a sample C, C++, and C++ PM program. The OS/2 Redbooks (see question 4.5) also have some sample code.

Are there any OS/2 programming classes or seminars?

Yes. Call IBM at either 1-800-3-IBM-OS2 in U.S. (or the PS/2 Help Center). Local IBM branches frequently hold OS/2 classes and seminars. I haven't seen third party efforts in this regard, but I know they exist.

See pub/os2/2.0/info/ivleague.txt on ftp-os2 for a list of third-party support organizations.

What are good reference books for programming in OS/2 and PM?

Van Nostrand Reinhold publishes a number of books on OS/2 2.0. Those that relate to programming are:

By William H. Zack
By Robert Orfali and Daniel Harkey, IBM Corporation
By Steven J. Mastrianni; Foreword by John Soyring, IBM Corporation
OS/2 2.0 PRESENTATION MANAGER GPI: A Programming Guide to Text, Graphics, And Printing
By Graham C.E. Winn, IBM Corporation
By David M. Dill, Consultant
By Stephen Knight, IBM Corportaion

Also see the information about redbooks in answer 4.5.

What are the OS/2 redbooks, and how do I get them?

IBM publishes so-called "redbooks" on many products, including OS/2 2.0. They seem to be a combination of power-user's guides and design information that may be of use to both users and programmers [I haven't received my copies yet, so I cannot say for sure.] These are usually intended only for special IBM customers and contain documentation that is generally unavailable anywhere else. You can order these books directly from IBM (see below). All of the following names are implicitly preceeded by "OS/2 Version 2.0."

Volume 1: Control Program: GG24-3730, $4.15

Technical information on Memory Management, Task Mangement, Support, Installation Considerations, Hardware Considerations, Boot Manager, National Language Considerations, Intel 386 architecture, Channel Architecture and SCSI. Documents config.sys.

Volume 2: DOS and Windows Environment, GG24-3731, $6.20

MVDM,8086 Emulation,MVDM DOS emulation, Device Drivers, Memory Extender Support, Installing and Migrating Applications, Windows Applications, DPMI, Running DOS apps,DOS settings, VMB.

Volume 3: PM and Workplace Shell GG24-3732, $3.65

Available now, but I don't know precisely what's in it.

Volume 4: Application Development GG24-3774, $5.25

Technical programming info (includes list in C) Overview, Object-Oriented Apps, PM application model, flat memory model, building PM app, Workplace AOAShell and System Object Model, Direct Manipulation (Drag/drop), PM resources, Multitasking Considerations, SAA CUA considerations, App Migration, Mixing 16 and 32 bit application modules, compiling and link editing (SOM), Adding Online Help, Problem Determination, Managing Development, Naming conventions.

Volume 5: Print Subsystem, GG24-3775, $5.20

Not Available yet.

The special part number GBOF-2254 is for all currently available volumes (presently 1-4).


The OS/2 2.0 Redbooks are available from IBM's TeleServices customer support number. The number is 1-800-7654-IBM (1-800-765-4426). You can pay by credit card or mail in a check after calling. The order will take about 2 weeks but can be sped up by paying for faster shipping.

You can also order the redbooks from your local IBM Branch Office library. Some possibly useful phone numbers are included here.

IBM Central Library, Los Angeles CA: (213) 621-6710
P.O. Box 60737
Los Angeles, CA 90060
Canada: (800) 465-1234, ext 4205 ($33.52)
UK: (0256) 478166, (#36.51, credit cards accepted)
Australia (Victoria): 698-1234 ($46.80 A)
IBM Australia
The Library
211 Sturt Street
South Melbourne, 3205
Att: Kate Seeley
Denmark: 33 32 40 55 (dkk 310)


What is available for multimedia programming under OS/2?

The OS/2 2.0 Multimedia package is now available. Call the IBM Multimedia office at (800) 426-9402 ext. 150.

What is available for AI/neural net programming under OS/2?

LISP and XScheme are available from hobbes. There are also some AI/neural net tools listed in tinf26.zoo.