LINUX vs. Windows NT or CE

Comparing Embedded Linux to Windows NT and CE
Embedded systems are generally found inside OEM products. They are typically characterized as being small systems with a mission to perform specific functions that comprise the intended product. Being an OEM product, cost is usually a significant or dominant consideration, as is performance. Embedded systems often are “blind nodes” with no operator interface of their own. Sometimes they use a commercial (and these days, low cost) external display device or rely on web or remote connections for operator functions. Ease of development and flexibility certainly play important roles in picking an operating system.

To meet these requirements, SIXNET has selected Linux for its clear advantages. Here are some of the main reasons why:

• Linux itself is free. This is already one significant cost advantage to an OEM.
• A wealth of General Public License utilities are available – also for free.
• Linux is a truly open operating system – you get the source code. You can make it do what you need, in the way you need to do it.
• Embedded Linux requires only a few Megabytes of memory. By way of example, the SIXNET IPm, including the entire suite of SIXNET firmware, a rich suite of Linux utilities and the complete ISaGRAF run time (all six languages) resides in less than four Megabytes of memory. (Embedded NT says that it will run in 32 Meg, but you better give it 64 Meg– or more).
• Linux is a fully featured operating system. As a form of Unix, it provides more than 30 years of maturity and proven results – which includes scalability to the largest systems.
• The technical advantages of Linux are almost endless. For example, embedded Linux systems (such as the SIXNET IPm) provide file journaling, which insures the integrity of the file system. (Data is not lost if the power fails at the wrong time.)
• Success in embedded Linux systems has been achieved down to the 10 microsecond (uS) level.
• Embedded systems need connectivity to Windows computers and in this regard, Linux is fully compatible. An embedded Linux system will appear to be a network drive to a Windows computer. Files can be shared on an open basis. (The embedded Linux system might as well be a Windows computer itself.) Then, there is telnet, ftp and many features and connectivity tools too numerous to mention.
• Linux continues to improve at the speed of light – more performance, new features, smaller size.
• A true testimonial to the advantages of embedded Linux is found in the SIXNET IPm Subsystem – less than seven square inches of real estate, -40 to +70 °C operation, less than two watts of power, free GPL (general public license) firmware – all for less than US$400 (OEM quantities) and that includes all of the necessary memory.

• Embedded Windows NT is at least as reliable as the Microsoft platform it is based upon. (Forgive our sarcasm.)
• Embedded NT carries the burden of licensing costs to Microsoft.
• Embedded NT is a proprietary operating system. (You cannot get it from anyone other than Microsoft.)
• All Microsoft products are closed (proprietary) software. You cannot get the source code and you can’t alter or extend their performance.
• Embedded NT requires 32 Megabytes or more of memory.
• Each new release historically requires more memory to support it. (The term “bloatware” comes to mind.)
• Embedded NT developers report a performance ceiling at 10 mS (if the applications you are running will cooperate and run at that speed – without causing delays or hogging the CPU). If they don’t – well, you may have trouble – you certainly cannot alter commercial NT applications to speed them up or remove unnecessary functionality.
• An OEM needs technical and economic stability (no new costs and licensing restrictions and continued support of legacy features). These are not historically Microsoft attributes. In fact its fair to say that Bill Gates is always looking for new revenue sources. (This in spite of the fact that most of Microsoft’s customers are OEMs.)

• Windows CE is not an operating system; it is merely an embedded kernel. (For example, a user cannot add applications by simply installing them. The words “compiling” and “linking” are often heard in this regard.) CE is an embedded kernel that may be adapted for OEM use in a specific product.
• Windows CE is licensed for OEM use – subject of course to Microsoft’s terms, conditions (and therefore restrictions) – for a licensing fee per copy.
• Contrary to popular belief (unethically fostered by Microsoft), Windows CE is NOT a stripped down version of Windows. It was separately developed (not even by Microsoft) and has struggled for compatibility throughout its life. Developers may anticipate the need to “port” applications intended to run on CE. (Expect high development time, frustration, and design compromises.)
• One strength of Windows CE is its support of a pseudo-Windows GUI. Many embedded systems however do not require a full graphical interface of their own, since they rely on network connections (and perhaps a browser) for an interface. If you don’t need a GUI, why would you consider a “Windows” operating platform? Which brings up an interesting point:
  • “Windows” operating systems were developed around their GUI. Performance of the applications that run within its environment has always been secondary. This is NOT in the best interests of industrial system designers – especially designers of real-time systems.
• Industrial applications are not important to Microsoft and they do not devote significant resources to meeting the needs of real-time system designers.
• An OEM needs technical and economic stability (no new costs and licensing restrictions and continued support of legacy features). These are not historically Microsoft attributes.