3 prom reading procedure – NEC uPD78P078 User Manual

Page 578

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CHAPTER 27

µ

PD78P078, 78P078Y

27.3.3 PROM reading procedure

PROM contents can be read onto the external data bus (D0 to D7) using the following procedure.

(1) Fix the RESET pin low, and supply +5 V to the V

PP

pin. Unused pins are handled as shown in, 1.5 (2) PROM

programming mode and 2.5 Pin Configuration (Top View).

(2) Supply +5 V to the V

DD

and V

PP

pins.

(3) Input address of data to be read to pins A0 through A16.

(4) Read mode.

(5) Output data to pins D0 through D7.

The timing for steps (2) through (5) above is shown in Figure 27-7.

Figure 27-7. PROM Read Timing

Address Input

A0 to A16

CE (Input)

OE (Input)

D0 to D7

Hi-Z

Hi-Z

Data output

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