I would argue that the native word size is still 32 bits on x86-64, though. With many instructions, using 64-bit registers needs a segment prefix override. Some

I would argue that the native word size is still 32 bits on x86-64, though. With many instructions, using 64-bit registers needs a segment prefix override. Some RISC architectures do not even have 32-bit zero-extending integer instructions, so for them, 64-bit as the native word size makes sense. On the other hand, I'm not sure if <stdint.h> and uint16_t were invented at the time, and “short short int“ is not valid syntax (even today), so there wasn't an obvious way to denote a 16-bit integer type.