Raised Cosine Key Shaper chip that can be used with the 5W HF PA kit to make a standalone PA with raised cosine RF envelope shape for click-free CW keying. Please refer to App Note AN005 for details.  

Note that this chip may be supplied as one of the following, depending on availability. They are functionally identical:

RC1: programmed ATtiny84 microcontroller chip
RC1a: programmed ATtiny24 microcontroller chip

This chip is not user re-programmable, because of the fuse settings which configure the /Reset pin as an I/O pin.