This is an Atmel (now Microchip) part with the 8 bit AVR risc instruction set. The interesting thing is that it is in an 8 pin DIP (or surface mount) package, and sells for as little at 53 cents. I first got interested in them because they are used in a lot of flashlights and I wanted to flash some new flashlight firmware.
I should note that these are the low end of a series of parts, and anyone with ideas of developing projects ought to just go to the high end and use the ATtiny85 with 8 times as much memory (and a price of $1.00 instead of 50 cents). Clearly the 13A parts are used in flashlights in order to pinch a few pennies. For the experimenter making just one or two projects there is not reason to save a few cents.
Tom's Electronics pages / tom@mmto.org