UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 185

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

(b) Control signal input/output mode
(i)
(ii) RD (Read Strobe)
(iii) WR (Write Strobe)
(iv) WAIT (Wait)
(v) HLDRQ (Hold Request)
(vi) HLDAK (Hold Acknowledge)
(vii) REFRQ (Refresh Request)
A16 to A19 (Address Bus)
Upper address bus output pins when the external memory space is extended (10000H-FFFFFH).
These pins operate in accordance with the memory extension mode register (MM).
The strobe signal for an external memory read operation. The operation of this pin is controlled by the memory
extension mode register (MM).
This pin of the PD784021 usually operates as an RD pin.
Pin that outputs the strobe signal for an external memory write operation. The operation of this pin is controlled
by the memory extension mode register (MM).
This pin of the PD784021 usually operates as an WR pin.
Wait signal input pin. Operates in accordance with the programmable wait control registers (PWC1, PWC2).
External bus hold request signal input pin. Operates in accordance with the hold mode register (HLDM).
Bus hold acknowledge signal output pin. Operates in accordance with the hold mode register (HLDM).
This pin outputs refresh pulses to pseudo-static memory when this memory is connected to it externally. Operates
in accordance with the refresh mode register (RFM).
CHAPTER 5 PORT FUNCTIONS
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