UPD17704 Datasheet, PDF (84/356 Pages) NEC – 4-BIT SINGLE-CHIP MICROCONTROLLERS WITH DEDICATED HARDWARE FOR DIGITAL TUNING SYSTEM

µPD17704, 17705, 17707, 17708, 17709
8.5 Cautions on Using Register File
Keep in mind the following points (1) through (3) when using the write-only (W), read-only (R), and unused
registers of the control registers (addresses 00H through 3FH of the register file).
(1) An “undefined value” is read if a write-only register is read.
(2) Nothing is affected even if a read-only register is written.
(3) An “undefined value” is read if an unused register is read. Nor is anything affected if this register is
written.
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