Hardware manual

Microcomputer Technical Q&A
135
Q&A No.: QAH8S-247
Category: I/O Ports
Subject: Reserved Bits
Question
Write data rules are sometimes given for reserved bits in internal I/O registers. Is there any
problem with writing data other than that prescribed to these reserved bits?
Answer
Only the data prescribed in the manual should be written, otherwise correct operation is not
guaranteed. For example, the ICE and the production chip may operate differently.
Applicable Products
Applicability Series Applicability Series Applicability Series
Yes Entire H8S Series H8S/2655 H8S/2350
H8S/2355 H8S/2357 H8S/2345
H8S/2245 H8S/2148 H8S/2144
H8S/2138 H8S/2134 H8S/2128
H8S/2124 — — — —