NEC uPD78056Y - Manual (Page 476)

476
CHAPTER 19 SERIAL INTERFACE CHANNEL 2
[Example]
Occurrence of INTSER
EI
Main processing
7 clocks of CPU clock (MIN.)
(time from interrupt request to servicing)
Instructions
equivalent to
2205 CPU
clocks (MIN.)
are necessary.
MOV A, RXB
RETI
UART reception error interrupt
(INTSER) servicing