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RDOS A promising DOS (windows)
replacement. Worth watching, but written in hard to
maintain, hard to adapt, even harder to read assembler.
When will they ever learn?
Realtime OS
guaranteed, ultra-fast interrupt response times --
features known as determinism and low latency -- required
for heavy-duty, hard real-time applications: management
and monitoring, programmable logic controllers, sensors
and high-precision robotics, anti-lock-braking systems,
test and instrumentation, printers and networking.
The name Real-Time-Os should be reserved for systems
with a dedicated real-time interrupt handler sheme. In
reality it is not. Many systems call themselves
real-time-systems without this prerequisite.
REAL-TIME SOFTWARE REIGNS IN POST-PC
Why the concern about Microsoft's dominance of the PC's
operating system?
The future belongs to embedded systems, which rely on
real-time operating
systems (RTOSs). Warren Webb instructs on the finer
points of RTOSs: Some
stress speed, for example, while others stress
modularity. To help you
through the RTOS maze, Warren lists an impressive array
of RTOSs and
outlines their functions, features, and prices.
http://www.ednmag.com/ednmag/reg/2000/02172000/04cs.htm
- Microtec Research, VRTX
- Integrated Systems, pSOS
- QNX from QNX Software Systems
- VxWorks from Wind River Systems.
- Windows CE 3.0 (1999)
- QLX (?): Real-time-Unix.
- ISI's pSOSystem, the industry's leading RTOS with
over 4500 design wins, provides a complete RTOS support
solution.
Rhapsody (Apple Computer
Corporation)
Related to: MacOS
Rhapsody is the code name for a new operating system from
Apple Computer, Inc., designed to complement Mac OS by
providing a variety of high-end solutions. The Rhapsody
operating system, available on both PowerPC and
Pentium-class processors, provides preemptive
multitasking, protected memory, and other modern
operating system features.
Roadrunner
In traditional operating systems, input/output (I/O)
subsystems implement a push-pull environment that
provides system calls to allow user applications to pull
data from or push data to a device. An important set of
applications make combined use of push-pull to implement
simple streaming, i. e. data is moved from one device to
another with no transformations. Using push-pull I/O to
implement these applications does not provide maximum
performance. This work proposes a kernel design optimized
for simple streaming applications. The Roadrunner
operating system is being developed specifically to
implement multiple, concurrent, high-speed speed data
streams with Quality-of-Service (QOS) parameters.
REACTOS
(most active free NT alternative at the moment)
"ReactOS is a free and open-source operating system based on the Windows
NT architecture, providing support for existing applications and drivers,
and an alternative to the current dominant consumer and server operating
systems."
Why re-implement NT?
First of all, the 'Windows' the general public knows is actually just
one part of the modern Windows NT operating system. They usually mean
the Win32 subsystem, a layer that sits upon the NT kernel, providing the
user and application interface.
Most people think of 'NT' as 'WinNT 4', while in reality the term NT
refers to the NT series, which ranges from version 3 over NT5 (2000, XP,
2003) to NT6 (Vista, 2008 and 7).
The NTarchitecture was designed by a team lead by David Cutler, a former
lead developer of VMS. It took them more than 4 years to combine the
best of UNIX, VMS and OS/2 and create the NT architecture.
In contrast to UNIX, ReactOS was designed for people familiar and
comfortable with the Windows environment. Everything can be done through
the well known Win32 user interface and advanced users are free to
automate tasks with scripts or use the console.
"Change your OS, not your software!"
The ReactOS project reimplements a state-of-the-art and open NT-like
operating system based on the NT architecture. It comes with a WIN32
subsystem, NT driver compatibility and a handful of useful applications
and tools.
ReactOS combines the power and strengths of the NT kernel - which is
well known for its extensibility, portability, reliability, robustness,
performance and compatibility – with Win32 compatibility. In short, ReactOS is designed to be powerful and lightweight. You can
think of the term "lightweight" in the good old fashion of Win95, a
consistent user interface and small bundle of very common and useful
tools. Although lightweight, ReactOS offers a lot in comparison to
Windows 95, with an up-to-date experience as well as built from scratch
on a rock solid NT core.
ReactOS is free software, the source code of the whole system is
available for free and it is licensed under the GNU GPL license. "'Free'
as in 'free speech' and as in 'free beer'"
ReactOS does not phone home or track your usage, nor does it contain
spy-software. As a matter of fact, other well known competitors are
known for such practices.
Life with other operating systems tends to be a love-hate relationship,
with most people falling strongly on one side or the other. The ReactOS
project has a great community that is well appreciated."
REACTOS Homepage
Take part in the developpment of reactos
Support
REACTOS: donate, developpers, testers, writers.... needed!
Real-Time Mach Project
(Carnegie
Mellon University)
Related to: Mach
Real-Time Mach is a research prototype real-time
operating system intended for use as a vehicle for doing
real-time systems research. The system is being developed
by the ART Project in the School of Computer Science,
Carnegie Mellon University.
RTS-80(outdated)
RTS-80 was develloped in the 70ths and introduced in the
starting eighties. It was a real-time messages/semaphore-based
Multitask/Multiuser-System on the basis of the Z80 and
was CP/M compatible - the most used system in the
70th/80th. A huge software basis was thus available for
this system. Preemptive multitasking and run-time linking
(DLL's !) were features of RTS-80 from its very start,
features which Windows learnt only 10-15 years later.
RTS-80 had a command set comparable to UNIX, knew pipes
and all sort of redirections Unix was able to do. With
the aid of a memory management unit RTS-80 was able to
address 1Mbyte of memory, an unbelievable huge memory at
that time ( the 1983 available IBM-PC could address
maximaly 640kbyte, normally it was delivered with
64kbyte). The system featured a driver based IO-system
with semaphore locking, making extensions easy. RTS-80
could address harddisks up to 1GB, a hugeness only
reached in the 90th. At that time harddiscs of 10-30Mbyte
were usual (prices around 10.000$ !!). One of the biggest
advantages and at the same time the biggest drawback of
RTS-80 was that it was completely written in Assembler,
making it a very fast OS. On the other hand this made
porting to the emerging 16/32-bit processors a hard to
accomplish task. In the mid-eighties a version for the National 16032/32032 was introduced, but since National was unable
to sell these really fine processors, RTS-80/32 found no
market(see MicroProcessor).
Eventually National stopped production of these really
fine processors (beginning 90ths) which rivaled the much
later introduced 80486 in computing power.
The multitask-kernel of RTS-80 (without
filesystem, today we would call this a micro-kernel) was
distributed separately in source code. The kernel had due
to an elaborate design a very short reaction time in task
switching. A sophisticated interrupt handler sheme
guaranteed fastest response times. Non-blocking
techniques were used throughout. This was one of the
reasons why many robots in the automobile industry were
based on this multitask-kernel. RTS-80 is the seldom case
where a book of the author accompanied the system,
describing all essential internal workings. It appeared
in the late 80th
:"R.Bitsch:Multitask,multiuser,multi-processor-systems",Frankfurt/Thun.
It is now out of print and no more deliverable.
RTEMS (Redstone
Military Arsenal)
RTEMS is a real-time operating system for embedded
computer systems with the following features:
- support for homogeneous and heterogeneous
multiprocessor systems
- event-driven, priority-based, preemptive
scheduling
- optional rate monotonic scheduling
- intertask communication and synchronization
- responsive interrupt management
- dynamic memory allocation
RTMX
O/S
Group Members: RTMX Incorporated
RTMX is a commercial, BSD 4.4-derived, real-time system
that offers POSIX 1003.4 real-time programming support
with user tunability along with the standard UNIX
functionality of BSD networking, X windows, and a full C
development environment.
RTX
RTX is a very small, very fast real time executive that
utilizes signals and queuing as a basis for managing and
scheduling tasks. It becomes very easy to support
multiple processors, communication channels, and to
synchronize processes. RTX is completely free, but it is
not public-domain software. If you decide to use the
software, you may receive an automatic license to do so
even in commercial products, if you provide adequate,
reasonable credit to its developer.
RXDOS
One of the many assembler Dos-clones.
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