| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly safe start information rewrite device which can rewrite start information easily after building up a device, and further, can prevent destruction of start information even if a bug or an operational mistake occurs during rewriting and cope with a rewrite request. SOLUTION: F.ROM 2 has an implementation block 2-1 and a spare block 2-2 both of which have a bootstrap in store. A write protecting circuit 4 inhibits write operation on to the implementation block 2-1. An address swap circuit 3 swaps the bootstraps in the implementation block 2-1 and in the spare block 2-2 in response to a special operation when power is applied. After deleting contents of the spare block 2-2 and replacing them with a new bootstrap input from the outside according to a rewrite program in the bootstrap, the address swap circuit 3 swaps the bootstraps in the implementation block 2-1 and spare block 2-2.
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