NEC PD17062 Manuale Utente

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When the 17K series assembler and emulator are used for data transfer with peripheral hardware via the

data buffer, note the following regarding unused peripheral addresses and write only (PUT only) and read

only (GET only) peripheral registers.

Reading from a write only peripheral register returns an unpredictable value.

Writing to a read only register does not change its contents.

Reading from an unused address returns an unpredictable value.  Writing to an unused address does not

change its contents.

An instruction that reads from a write only register generates an error.

An instruction that writes to a read only register generates an error.

An instruction that reads from or writes to an unused address generates an error.

(3) When using an emulator (used to execute instructions by batch processing, etc.)

Reading from a write only register returns an unpredictable value and does not generate an error.

Writing to a read only register does not change its contents and does not generate an error.

Reading from an unused address returns an unpredictable value.  Writing to an unused address does not

change its contents and does not generate an error.