UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 626

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

(2) Programmable wait control registers (PWC1/PWC2)
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The PWC1 and PWC2 specify the number of waits.
PWC1 is an 8-bit register that divides the space from 0 to FFFFH into four, and specifies wait control for each of these
four spaces. PWC2 is a 16-bit register that divides the space from 10000H to FFFFH into four, and specifies wait control
for each of these four spaces.
The PWC1 can be read or written to with an 8-bit manipulation instruction, and the PWC2 with a 16-bit manipulation
instruction. The PWC1 and PWC2 formats are shown in Figure 21-9.
The high-order 8 bits of the PWC2 are fixed at AAH, and therefore ensure that the high-order 8 bits are set to AAH.
When RESET is input, the PWC1 is set to AAH, and the PWC2 to AAAAH, and 2-wait insertion is performed on the
entire space.
Caution Do not set external wait for the internal ROM area. If external wait is set for the internal ROM area,
the CPU is deadlocked. This deadlock status can be cleared only by reset input.
CHAPTER 21 LOCAL BUS INTERFACE FUNCTION