UPD784938 Datasheet, PDF (175/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
(ii) RD (Read Strobe)
The strobe signal for an external memory read operation. The operation of this pin is controlled by the memory
expansion mode register (MM).
(iii) WR (Write Strobe)
Pin that outputs the strobe signal for an external memory write operation. The operation of this pin is controlled
by the memory expansion mode register (MM).
(iv) WAIT (Wait)
Wait signal input pin. Operates in accordance with the programmable wait control registers (PWC1, PWC2).
(v) HLDRQ (Hold Request)
External bus hold request signal input pin. Operates in accordance with the hold mode register (HLDM).
(vi) HLDAK (Hold Acknowledge)
Bus hold acknowledge signal output pin. Operates in accordance with the hold mode register (HLDM).
(vii) REFRQ (Refresh Request)
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).
Figure 6-55. Port 6 Mode Register (PM6) Format
PM6
7
6
5
4
3
2
1
0 Address After reset R/W
PM67 PM66 PM65 PM64 PM63 PM62 PM61 PM60 0FF26H
FFH
R/W
PM6n P6n Pin Input/Output Mode Specification
(n = 0 to 7)
0 Output mode (output buffer on)
1 Intput mode (output buffer off)
Preliminary User’s Manual U13987EJ1V0UM00
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