PIC10F206 - 8Pin 4MHz 512byte
The PIC10F206 devices from Microchip Technology are low-cost, high-performance, 8-bit, fully-static, Flash-based CMOS microcontrollers. They employ a RISC architecture with only 33 single-word/single-cycle instructions. All instructions are single cycle (1μs) except for program branches, which take two cycles.
High performance FLASH microcontroller that can be erased and reprogrammed without having to use a UV light source. This allows the same device to be used for prototype development as well as production. The PIC10F206 has 0.75k of code space, 24 bytes of RAM and 4Mhz Internal Oscilator.
Can work down to 2V!