SCALABILITY

Because the different parts of the On Time RTOS are modules linked from a library, only those parts used by the application are included automatically. The RTTarget-32 RTOS core and all extensions are supplied as linkable libraries.

A minimal RTTarget-32 program runs in about 12 KB of ROM and 4 KB of RAM (or 16 KB of RAM in systems booted from disk). An application linked with all of the available extensions (RTKernel-32, RTFiles-32, RTIP, floating-point emulator, and DLL loader) requires about 128 KB of ROM and 128 KB of RAM.

The On Time RTOS isn’t a Windows NT clone. Only a subset of NT’s API is supported to keep the resource requirements small. For example, only console mode apps without a GUI are supported although graphics programming is possible using an add-on graphics library.

The On Time RTOS does not support Windows NT or Windows 95 device drivers, but real-time embedded systems often have to deal with proprietary hardware. Here, RTTarget-32’s support for port I/O, interrupt handling, and access to the physical address space from within the application code makes life easier for developers.

With so many options, finding the right OS for real-time embedded systems can be challenging. By using a Win32-compatible RTOS, you can leverage the technology base of standard PC hardware and software and put it to use in the world of embedded systems.

Peter Petersen has done research in the field of massively parallel real-time data acquisition at DESY (German Electron Synchrotron). He contributed to the development of an Ada compiler for a multi-processor computer system before founding On Time in 1989. You may reach him at pp@on-time.de.

Tom Schotland studied mathematics and computer science and worked as a real-time programmer in neuroscience laboratories before joining On Time in 1993. You may reach him at tom@on-time.com.