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.eCos Many other free software embedded systems are also available at Cygnus' ftp site or on their sourcecode page.Cygnus' ftp sitesourcecode

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.Chorus MachslidesFAQhere Nexus' coniX small romable embedded operating system for ARM processors.coniX

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.DR-DOS 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.JavaOS JavaSoft Microware's OS-9 real-time OS, widely used, and still in good shape after so many years.OS-9

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.PalmOS 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.QNXQNX papers Michael Podanoffsky's RxDOS is also being marketed as a solution for embedded systems now.RxDOS

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.Symbian Wind River's VxWorks real-time operating system, micro-kernel based, POSIX and ANSI C compliant.VxWorks 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.Windows CE

Unix Style OS Linux, RT Linux Mobile Linux VxWorks Wind River Systems – Lots of debugging support tools, used on Mars Pathfinder BeOS – for Internet Appliances, good multitasking. Free download 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 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