BTW, there are also other interesting, low-power RISC architectures that are used in millions of devices, but most people have never heard of them. For example:
* SuperH [0], 32bit only, now basically dead, but microcontrollers are still available
* AVR32 [1], 32 bit only, also quite dead
* ARC [2], 32/64bit, still quite popular in an automotive
IIRC Arm licensed 'short instruction' encoding from Hitachi where it had been used SuperH to create Thumb which was key in getting Arm into phones.