Using 8253 and 8255 sent out the sound with fixed frequency.

并利用8253定时器和8255可编程控制器发出了指定频率的声音。

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With fixed frequency control circuit, it provides with over voltage, over current, overheat and short circuit protection.

该系列电源适配器，采用固定频率控制电路，具备限流、限压、过温、短路全功能保护。

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The fixed frequency sample PWM method is put forward in this paper together with the theoretical analysis about their switch strategy.

本文提出恒频采样电流跟踪型PWM方式，并对其开关策略进行了理论分析。

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Unlike traditional keyboards that place your hands in a rigid position, the Engage Keyboard features a patented motion system that studies your typing frequency and makes subtle, comfortable adjustments periodically so your hands and wrists are never in a fixed position while you work.

ENGADGET: Smartfish Engage keyboard automates ergonomics, is finally available