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 On Time RTOS-32 Documentation
 Welcome
 RTTarget-32
RTTarget-32 Programming Manual
 Introduction
Running Win32 Programs without Win32
 Benefits of Running without Windows
Benefits of Running with Windows
Preparing a Program for RTTarget-32
Locating a Program
Cross Debugging a Program
A Complete Example
The i386 Microprocessor
RTLoc: Locating a Program
Running a Program on the Target
Cross Debugging
Using an IDE
The RTTarget-32 API
Demo Programs
Advanced Topics
Compiling and Linking with On Time RTOS-32
Redistributable Components of RTTarget-32
RTLoc Error Messages
RTTarget-32 Reference Manual
RTKernel-32
RTFiles-32
RTIP-32
RTPEG-32
RTUSB-32
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Running Win32 Programs without Win32
Windows is a complex operating system offering a comprehensive set of API functions. They fulfill widely differing application program requirements, but their drawback is a substantial overhead on system resources like main memory and disk space, even at times when not all system services are actually required. Moreover, the security mechanisms provided by these systems can further increase the run-time overhead. For example, hardware access and interrupt processing must be placed in device drivers. However, device drivers are difficult to program and to debug, and access from application programs is slow. Most importantly, high interrupt latencies and the non-deterministic time behavior of Windows' tasking makes Windows unsuitable for real-time systems.
Embedded systems typically will not need all services offered by Windows, but will often require low interrupt response times. Also, the cost of RAM, disk space, and run-time royalties of systems running Windows may be prohibitive for systems built in large quantities.
RTTarget-32 allows running Win32 programs without Windows. Basically, three steps are required to achieve this goal:
- Absolute addresses must be supplied for the program. Windows can usually load a program at any address. The executable file contains a fixup table specifying the locations in the program image that need to be adjusted. This is called fixing-up or locating.
- Substitutes for commonly used Win32 API functions must be supplied. Most Win32 programs will contain calls to the Win32 API library. RTTarget-32 supports a subset of the Win32 API large enough to support the standard C/C++ and Pascal run-time libraries and most programs using character-mode user interfaces.
- The target computer must be booted. This process includes initialization of the hardware and activating the application.
As an additional aid for software development, RTTarget-32 also supports debugging programs while they are running on the target.
 Introduction
 Benefits of Running without Windows
Benefits of Running with Windows
Preparing a Program for RTTarget-32
Locating a Program
Cross Debugging a Program
A Complete Example
 The i386 Microprocessor
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