What is the difference between RCR and ROR?

Question

I understand the from the terms that RCR would rotate the bit from the right to left, taking the bit from the carry while ROR will

Answer 1

RCR includes the carry flag in the rotation, so it's effectively an N+1 bit rotate, whereas ROR does not include the carry flag, so it's just an N bit rotate.

Some nice diagrams from www.c-jump.com:

Answer 2

Both instructions rotate bits from left to right (where the left hand bit is the MSB).

RCR rotates the carry flag into the MSB and the LSB to the carry flag.

ROR rotates the LSB to the MSB without going through the carry flag.

+--> CF -->  MSB --> ... -> LSB --+
|                                 |      RCR
+---------------------------------+


+-> CF      +-> MSB --> ... -> LSB --+
|           |                        |      ROR
+------------------------------------+