Audio Controller Integrated Circuits - HK722

 Audio echo processor IC .
 Echo mode at 20.5ms ~ 163.8
   ms & surround mode at 4.1ms 
   ~ 41ms ( oscillator frequency 
   base on 6 MHz ) . 
 Built in adjustable oscillator .
 Built in power on reset circuit .
 Built in 30K bits SRAM for 
   delay control .
 Direct control and  micro-  
   processor control interface .
 Auto muting during power up 
   and change mode .