IntroductionThe 8253 is a programmable interval timer/counter specifically designed for use in real-time application for timing and counting functions such as binary counting, generation of accurate time delay, generation of square waves, rate generation, hardware/software triggered strobe signal, one-shot signal of desired width, etc. The function of the 8253 timer is that of a general-purpose, multi-timing element which can be treated as an array of I/O ports in the system software.
8253 can operate in the following modes.
Mode 0 Interrupt on terminal countMode 1 Programmable one-shotMode 2 Rate generator
Mode 3 Square-wave generator
Mode 4 Software triggered mode
Mode 5 Hardware triggered mode