Hardware manual

Microcomputer Technical Q&A

Q&A No.: QAH8S-004

Category: CPU

Subject: Area Usable as ROM in Vector Table

Questions

1. Can a free area in the vector table (reserved, or reserved for system use) be used as ROM?

2. Can a free area in the internal I/O register area by used as ROM?

Answers

1. Vector numbers 0 to 6 and 12 to 15 reserved for system use in the vector table cannot be used.

Reserved addresses can be used as ROM. Vector addresses for unused interrupts in the vector

table can also be used as ROM.

2. Free I/O register areas cannot be used.

Additional Explanation

Areas reserved for system use can be used by development tools.

Addresses of areas reserved for system use, and reserved area addresses, should be checked

manually.

In a memory-indirect-addressing branch address area, addresses other than those reserved for

system use and the used vector table addresses can be used.

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 — — — —