这是一张通用定时器/计数器卡你可以绕线在我们…

This is a photo of a general purpose timer/counter card you can wirewrap in a weekend. It plugs into your PC s ISA bus just like a sound or modem card. It gives high-resolution timing (microseconds). Because of its programmablity, it is very powerful and flexible. You can even control DC or servo motors using pulse-width modulated (PWM), or stepper motors using its square wave capabilities. The figure below is the actual output (square wave) from the 8254 card captured by an oscilloscope:

8254.htm