SNIU028E February 2016 – February 2025 UCD3138 , UCD3138064 , UCD3138064A , UCD3138128 , UCD3138A , UCD3138A64
The DEC register has an RONLY bit as well. If set, this means “read only”. An attempt to write to a memory space with the RONLY bit set will cause an illegal access exception, which will normally reset the processor. This bit may be set to cause device reset if the program runs away either due to a program bug or an input glitch.