Embedded OS Options

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Embedded OS Options
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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.
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• 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.

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• 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.

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• 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.

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• 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,
  real-time, 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.

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• 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.
  

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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

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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.

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Factors in Selecting an OS

• 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