Introduction

Thread response times have been improved in Windows CE 3.0 by the tightening of the upper bounds on scheduling latencies for high-priority Interrupt Service Threads (IST). This improvement in thread response allows developers to know specifically when the thread transitions occur, and aids them in creating new embedded applications by increasing the capabilities of monitoring and controlling hardware in Windows CE.

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  Shorter Interrupt Service Routine (ISR) latencies. Because the kernel uses the interrupt ID that is provided by the ISR to set the event that the IST is waiting on, a short ISR latency is essential for a real-time system.
  
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  Support for nested interrupts. Support has been added for nested interrupts, which allows interrupts at higher priority levels to be serviced immediately, instead of potentially waiting for a lower-priority ISR to complete.
  
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  Increased priority levels. Additional priority levels (a total of 256) allow users more flexibility in controlling the scheduling of embedded systems.
  
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  Support for semaphores. In addition to the currently supported mutexes and events, Windows CE has been expanded to support semaphores.
  
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  The ability to change the quantum of any thread in the system. This includes support for two APIs: CeSetThreadQuantum and CeGetThreadQuantum.
  
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  Kernel-level security. A new security model restricts access to system APIs that a rogue application could call to damage the platform. An OEM can specify whether modules and processes can run or not run and specify those that are fully trusted on a particular platform. Two new APIs allow software developers to retrieve the assigned trust level of a module or a process.