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Embedded OS Options
Operating systems for embedded devices
As embedded systems (PDAs, cellphones,
point-of-sale devices, VCRs, industrial robot
control, or even your toaster) become more
complex hardware-wise with every generation,
and more features are put into them by the day,
applications they run require more and more to
run on actual operating system code in order to
keep the development time reasonable.
The free OS options:
•eCos from Cygnus Solutions, an
operating system runtime compatible
with the japanese norm µITron, with
complete source code available, and
FREE.
•Many other free software embedded
systems are also available at Cygnus' ftp
site or on their sourcecode page.
OS Royalties Required:
•Chorus is a proprietary microkernel rival of
Mach, and a RTOS (now acquired by Sun
Microsystems) for telecommunication devices
(cellphones, etc.) and network appliances
(webphones, set top boxes..). See some slides
about it, and a FAQ) is available here. There
also are tech reports here.
•Nexus' coniX small romable embedded
operating system for ARM processors.
•Caldera Thin Clients' DR-DOS (OpenDOS) is now
being sold as a solution for embedded systems. It
has a full-featured web browser fitting in 4 MB of
memory.
•Sun's JavaOS (with a more technical page at
JavaSoft) was a standalone virtual machine not
running on top of any other OS; mainly targetted at
embedded systems. Proprietary project dropped.
•Microware's OS-9 real-time OS, widely used, and
still in good shape after so many years.
•Palm Computing's PalmOS for the Palm Pilot and
soon a flurry of other mobile products. Currently
the leader OS for PDAs, has many applications and
supporting companies.
•QNX is a an effective, scalable, POSIX emulation
capable, message passing, micro-kernel based, realtime, distributable, OS that has proven successful in
this embedded market and/or on x86 systems. See
their QNX papers.
•Michael Podanoffsky's RxDOS is also being
marketed as a solution for embedded systems now.
•Symbian, formerly known as EPOC32, the OS at
the heart of PSION hardware and an increasing
number of telephony, telecommunication, PDA, etc.
products. A very classical and absolutely
uninventive architecture, but that is well respected
and stable.
•Wind River's VxWorks real-time operating system,
micro-kernel based, POSIX and ANSI C compliant.
•Microsoft's attempts at fitting a large desktop-PC
operating system into the stringent requirements of
embedded systems are here: Windows CE and their
latest, Windows XP Embedded.
Unix Style OS
• Linux, RT Linux
• Mobile Linux
• VxWorks Wind River Systems – Lots of
debugging support tools, used on Mars Pathfinder
www.windriver.com
• BeOS – for Internet Appliances, good
multitasking. Free download
www.be.com
• QNX, many others
Windows Style OS
• Windows 98 and NT (2000) used in some
systems. NT has slow real time response.
• Windows XP Embedded (new)
• Windows CE for smaller systems
• Both use Windows API calls, CE supports a
subset of API calls.
Factors in Selecting an OS
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Memory Size & Power
Processor Support
Performance, Security, Networking
Virtual memory and Disk Storage
Use Flash/ROM instead of Disk?
No console or keyboard?
Support for Devices – Device Drivers?
Available applications and support tools
Real Time constraints of product
User Interface – Window GUI?
License Fees
Time to develop product