Rick Grehan
Every time it looks like MS-DOS has overstayed its welcome and is about to be shouldered out by a bigger and better operating system, something comes along and suddenly, DOS doesn't look so bad. The latest development of this nature is Phar Lap's TNT DOS-Extender, a much-expanded version of that company's
386 | DOS-Extender product. What makes TNT special (and what gives it its name) is that it's a DOS-extender injected with Windows NT's nongraphical goodies. Think of TNT as Windows NT without the Windows part: multiple processes, threads, semaphores, virtual memory, memory-mapped files, and even DLLs. Once compiled with TNT, your program can run unchanged as a DOS, Windows 3.x, or native character-mode NT application. TNT supports a subset of the NT API, so it's compatib
le with Microsoft's 32-bit Visual C++ compiler. Microsoft even licensed NT's floating-point emulation library to Phar Lap so that a TNT application you run under DOS will give you identical floating-point results when you run it as a native NT program.
Currently, although TNT is compatible with Microsoft's 32-bit Visual C++, MetaWare's High C/C++, and Watcom's C/C++ 32 (as well as other language compilers such as Lahey FORTRAN), only Visual C++ allows access to the NT components of TNT. You can use the other compilers with TNT to create
386 | DOS-Extender-compatible applications (referred to as DOS-style programs). Look for more compilers to provide the NT support for TNT in the near future.
Microsoft uses TNT as the DOS-extender that drives the DOS command-line versions of its 16-bit and 32-bit Visual C++ compilers. Denis Gilbert, Microsoft's general manager of the Visual C++ business unit, sees TNT as a way for developers to hedge their bets. "Developers can build 32-bit applications that
run on DOS and Windows today and will run unchanged in NT tomorrow." Furthermore, Gilbert points out that TNT allows companies to develop NT-style applications that can run on hardware (e.g., 386SX laptops) that may simply be unable to support NT.
The TNT developer's kit is $495--that gets you the extender, assembler, linker, librarian, and two debuggers (including the 32-bit version of Microsoft's CodeView). If you want to distribute your application, however, you've got to purchase the $1995 run-time kit to bind the extender into your executable file. The run-time kit also includes a license for distributing your application's first 1000 copies (Phar Lap Software of Cambridge, Massachusetts, (617) 661-1510, tells me that price is negotiable.)
Of course, it's tempting to wonder about TNT's lifespan. Couldn't the widespread acceptance of NT or the movement of advanced 32-bit features into future versions of DOS simply obviate it? Possibly, but TNT is here now, and the applications you build with
it will run in 32-bit glory, immune to the evolution of DOS or NT.
Illustration: Over 1200 applications are built with versions of Phar Lap's extender, ranging from CAD to database to games like Access Software's Links 386 Pro for DOS.
Phar Lap's TNT Adds Life to MS-DOS
