The Motorola 68HC11 (6811 for short) is a microcontroller family from Motorola, descended from the Motorola 6800 microprocessor. The 68HC11 devices are more powerful and more expensive than the 68HC05 family.
It is a microcontroller used in barcode readers, hotel card key writers, and various other embedded systems. It has an instruction set compatible with the 6801 and 6809, with the addition of a Y register (instructions are the same as for the X register, with a prefixed 18 or some other byte). It has two eight-bit accumulators, A and B, two sixteen-bit index registers, X and Y, a processor flag register, a stack pointer, and a program counter.
The 6811 has five external ports, A, B, C, D, and E, each eight bits except for D which is six. It can be operated with an internal program and RAM or an external memory. With external memory, B and C are used as address and data bus. To get them back, one can attach a port replicator unit to the 6811. Port A has input capture, output compare, and other timer functions, port D has serial I/O, and port E has an analog to digital converter.
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