英语翻译ADSL:standards,implementation,and architectureWindows CE

英语翻译
ADSL:standards,implementation,and architecture
Windows CE (also known officially as Windows Embedded CE since version 6.0[2][3],and sometimes abbreviated WinCE) is a variation of Microsoft's Windows operating system for minimalistic computers and embedded systems.Windows CE is a distinctly different kernel,rather than a trimmed-down version of desktop Windows.It is not to be confused with Windows XP Embedded which is NT-based.It is supported on Intel x86 and compatibles,MIPS,ARM,and Hitachi SuperH processors.
Features
Windows CE is optimized for devices that have minimal storage—a Windows CE kernel may run in under a megabyte of memory.Devices are often configured without disk storage,and may be configured as a “closed” system that does not allow for end-user extension (for instance,it can be burned into ROM).Windows CE conforms to the definition of a real-time operating system,with a deterministic interrupt latency.It supports 256 priority levels and uses priority inheritance for dealing with priority inversion.The fundamental unit of execution is the thread.This helps to simplify the interface and improve execution time.
In the early days of DSL,installation required a technician to visit the premises.A splitter was installed near the demarcation point,from which a dedicated data line was installed.This way,the DSL signal is separated earlier and is not attenuated inside the customer premises.However,this procedure is costly,and also caused problems with customers complaining about having to wait for the technician to perform the installation.As a result,many DSL vendors started offering a self-install option,in which they ship equipment and instructions to the customer.Instead of separating the DSL signal at the demarcation point,the opposite is done:the DSL signal is "filtered off" at each phone outlet by use of a low pass filter,also known as microfilter.This method does not require any rewiring inside the customer premises.
A side effect of the move to the self-install model is that the DSL signal can be degraded,especially if more than 5 voiceband devices are connected to the line.The DSL signal is now present on all telephone wiring in the building,causing attenuation and echo.A way to circumvent this is to go back to the original model,and install one filter upstream from all telephone jacks in the building,except for the jack to which the DSL modem will be connected.Since this requires wiring changes by the customer and may not work on some household telephone wiring,it is rarely done.It is usually much easier to install filters at each telephone jack that is in use.

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