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Benefits of Running without Windows

The most important advantages of not using Windows are:

• Low resource requirements. RTTarget-32's boot code needs only about 6k of memory. Programs not using the run-time system can run in as little as 16k total memory. If the run-time system is used, about 64k is required for the heap and run-time system code.
• Low interrupt latencies. Using RTTarget-32, the interrupt latency can be as low as about 5 microseconds on a 16Mhz-386SX or EX. Under Windows, the same CPU can yield several milliseconds interrupt latency.
• Interrupt handlers in application code. RTTarget-32 allows the application to install interrupt handlers. This greatly simplifies the interaction with interrupt-generating hardware and is much faster than Windows device drivers.
• Hardware access. RTTarget-32 allows the application to directly access hardware through I/O ports or memory mapped I/O. No overhead is incurred by emulation or complicated device drivers. Windows does not permit applications to access devices directly.
• Physical memory access. RTTarget-32 initializes the CPU such that physical addresses are equal to virtual addresses used by the application, even if paging is used. This facilitates direct hardware access through memory mapped devices and the use of DMA. Windows does not allow access to physical addresses.
• Access to privileged instructions. RTTarget-32 can run applications at privilege level 3 or 0. Windows supports only privilege level 3 for applications.
• Speed. Windows needs a substantial amount of CPU time for system management. With RTTarget-32, this time is freed and made available to your application. Thus, most applications will run faster under RTTarget-32 than under Windows. In addition, RTTarget-32's deterministic behavior makes it suitable for real-time systems.

Running Win32 Programs without Win32

Benefits of Running with Windows