ROM patch function is to support repair of program at finding bug of program out.
This function is occurred interrupt by detecting to coincide with internal address, and this interrupt transaction is executed as program of actual patch transaction.
(Of course, program of patch transaction is unknown in advance. Therefore system in order to download from external memory (E2PROM or etc.) is needed at development of program.)
What is program patch processing?
Even if you found the BUGs after you made the MASK ROM, you can correct the program. To make the patch to MASK ROM, load the corrected program to internal RAM from external memory.
No need to remark the MASK ROM
No unnecessary stock
Can reduce the delay of product shipment
F2MC-16LX memory space
Program patch register x 2