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@c COPYRIGHT (c) 1988-2002.
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@c On-Line Applications Research Corporation (OAR).
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@c All rights reserved.
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@c
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@c basic.t,v 1.9 2002/01/17 21:47:44 joel Exp
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@c
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@chapter Basic Information
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The questions in this category are basic questions about RTEMS. Where
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did it come from, why is it, what is it, when should you use it, etc.?
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@section What does RTEMS stand for?
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RTEMS is an an acronym for the Real-Time Executive for Multiprocessor
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Systems.
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Initially RTEMS stood for the Real-Time Executive for Missile Systems
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but as it became clear that the application domains that could use
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RTEMS extended far beyond missiles, the "M" changed to mean Military.
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At one point, there were both Ada and C implementations of RTEMS. The
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C version changed the "M" to mean Multiprocessor while the Ada version
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remained with the "M" meaning Military.
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@section What is RTEMS?
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RTEMS is a real-time executive which provides a high performance
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environment for embedded military applications including many
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features. The following is just a short list of the features
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available in RTEMS. If you are interested in something that
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is not on this list, please contact the RTEMS Team. Features
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are being added continuously.
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@itemize @bullet
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@item Standards Compliant
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@itemize @bullet
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@item POSIX 1003.1b API including threads
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@item RTEID/ORKID based Classic API
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@end itemize
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@item TCP/IP Stack
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@itemize @bullet
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@item high performance port of FreeBSD TCP/IP stack
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@item UDP, TCP
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@item ICMP, DHCP, RARP
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@item TFTP
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@item RPC
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@item FTPD
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@item HTTPD
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@item CORBA
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@end itemize
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@item Debugging
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@itemize @bullet
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@item GNU debugger (gdb)
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@item DDD GUI interface to GDB
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@item thread aware
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@item debug over Ethernet
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@item debug over Serial Port
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@end itemize
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@item Filesystem Support
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@itemize @bullet
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@item In-Memory Filesystem (IMFS)
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@item TFTP Client Filesystem
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@end itemize
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@item Basic Kernel Features
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@itemize @bullet
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@item multitasking capabilities
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@item homogeneous and heterogeneous multiprocessor systems
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@item event-driven, priority-based, preemptive scheduling
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@item optional rate monotonic scheduling
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@item intertask communication and synchronization
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@item priority inheritance
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@item responsive interrupt management
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@item dynamic memory allocation
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@item high level of user configurability
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@end itemize
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@end itemize
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@section What standards does RTEMS support?
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The original "Classic" RTEMS API is based on the Real-Time Executive
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Interface Definition (RTEID) and the Open Real-Time Kernel Interface
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Definition (ORKID). RTEMS also includes support for POSIX threads
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and real-time extensions.
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With the addition of file system infrastructure, RTEMS supports
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about 70% of the POSIX 1003.1b-1996 standard. This standard
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defines the programming interfaces of standard UNIX. This means
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that much source code that works on UNIX, also works on RTEMS.
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@section What processors is RTEMS available for?
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RTEMS is available for the following processor families:
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@itemize @bullet
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@item Motorola MC68xxx
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@item Motorola MC683xx
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@item Motorola ColdFire
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@item Hitachi SH
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@item Intel i386
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@item Intel i960
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@item MIPS
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@item PowerPC
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@item SPARC
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@item AMD A29K
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@item Hewlett-Packard PA-RISC
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@end itemize
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In addition, there is a port to UNIX which can be used as a prototyping
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and simulation environment.
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@section Executive vs. Kernel vs. Operating System (RTOS)
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The developers of RTEMS developers use the terms executive and kernel
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interchangeably. In the embedded system community, the terms executive
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or kernel are generally used to refer to small operating systems.
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So we consider it proper to refer to RTEMS as an executive, a kernel,
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or an operating system.
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@section Where/why was it developed?
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RTEMS was developed by On-Line Applications Research Corporation (OAR)
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for the U.S. Army Missile Command prior to that organizations merger
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with the Aviation Command that resulted in the new command, U. S. Army
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Aviation and Missile command (AMCOM). The original goal of RTEMS was
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to provide a portable, standards-based real-time executive for which
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source code was available and royalties were paid.
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In other words, RTEMS was open source before open source was cool.
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@section Are there no similar commercial products?
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Yes, but not all are based on standards and the open source philosophy.
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@section How can I get RTEMS?
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RTEMS is distributed by OAR Corporation via the Internet. Point your
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favorite browser at the following URL and following the link:
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@c this version should work
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@c @set OAR-URL http://www.OARcorp.com
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@c @uref{@value{OAR-URL},@value{OAR-URL}}
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@uref{http://www.OARcorp.com,http://www.OARcorp.com}
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@section What about support?
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OAR Corporation provides numerous services for RTEMS including support,
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training, and custom development.
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@section Are there any mailing lists?
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The primary RTEMS mailing list is @code{rtems-users@@oarcorp.com}. This
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list is for general RTEMS discussions, questions, design help, advice,
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etc.. Subscribe by sending an empty mail
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message to @code{rtems-users-subscribe@@OARcorp.com}. This
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mailing list is archived at:
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@example
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http://www.oarcorp.com/rtems/maillistArchives/rtems-users
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@end example
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The @code{rtems-snapshots@@oarcorp.com} mailing list is for those
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interested in taking a more active role in the design, development,
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and maintenance of RTEMS. Discussions on this list tend to focus
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on problems in the development source, design of new features, problem
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reports, etc.. Subscribe by sending an empty mail
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message to @code{rtems-snapshots-subscribe@@OARcorp.com}.
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mailing list is archived at:
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@example
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http://www.oarcorp.com/rtems/maillistArchives/rtems-snapshots
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@end example
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The archives for both mailing lists include discussions back
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to 1997.
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@section Are there any license restrictions?
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RTEMS is licensed under a modified version of the GNU General Public License
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(GPL). The modification places no restrictions on the applications which
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use RTEMS but protects the interests of those who work on RTEMS.
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The TCP/IP network stack included with RTEMS is a port of the FreeBSD
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network stack and is licensed under different terms that also do not
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place restrictions on the application.
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@section Are there any export restrictions?
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No.
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