UPD784938 Datasheet, PDF (636/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 24 LOCAL BUS INTERFACE FUNCTION
24.5 Cautions
(1) When the bus hold function is used, the external wait function cannot be used (access wait control by means of the
WAIT pin), and 0, 1, or 2 waits must be selected for the entire space.
(2) The refresh function cannot be used when the bus hold function is used. In this case, ensure that refreshing is specified
as disabled.
(3) Do not set external wait to the internal ROM area. Otherwise, the CPU may be in the deadlock status which can be
cleared only by reset input.
(4) If the pseudo-static RAM refresh function is used when the address wait function is used, the refresh pulse is output
and, at the same time, the memory is accessed. Therefore, do not use the pseudo-static RAM refresh function when
using the address wait function.
Conversely do not use the address wait function when the pseudo-static RAM refresh function is used.
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Preliminary User’s Manual U13987EJ1V0UM00