Here is what is said in the megaAVR 0-series on 16 bit copies:
The wording seems to indicate that if I read the high byte, I get a read from the TEMP register.
But I'm wondering if there is some constraint with respect to this behavior. If I read the low byte 10,000 cycles ago, does the high byte still come from the TEMP register, or only if the low and high byte reads are performed with no intermediate instructions. Any ideas?
(I searched for TEMP register but the last post was in 2012.)