Tutorial 3 - About the Motorola MC 68HC11

• The 68HC11 is a powerful 8-bit data.
• 16-bit address microcontroller from Motorola (Now Freescale) with an instruction set that is similar to the older 68xx (6801, 6805, 6809) parts.
• Depending on the variety, the 68HC11 has built-in EEPROM/OTPROM, RAM, digital I/O, timers, A/D converter, PWM generator, and synchronous and asynchronous communications channels (RS232 and SPI).
• Typical current draw is less than 10mA.
• Optimized for low power consumption and high-performance operation at bus frequencies up to 4 MHz.
• The CPU has two 8 bit accumulators (A & B) that can be concatenated to provide a 16 bit double accumulator (D).
• Two 16 bit index registers are present (X & Y) to provide indexing to anywhere in the memory map.
  
• Having the two index registers means the 68HC11 is very good for processing data.

Details can be found HERE