12

µPD75P218

4.

PROM (PROGRAM MEMORY) WRITE AND VERIFY

The PROM contained in the

µPD75P218 is one-time PROM or EPROM for writing, erasing, and rewriting.

Table 4-1 shows the pin functions during the write and verify cycles. Note that it is not necessary to enter

an address, because the address is updated by pulsing the X1 clock pins.

Table 4-1 PROM Write and Verify Pin Functions

Pin Name

X1, X2

MD0 - MD3

P40 - P43 (Four low-order bits)

P50 - P53 (Four high-order bits)

Function

Normally 2.7 to 6 V; 12.5 V is applied during the write/verify cycles.

After a write/verify write, the X1 and X2 clock pins are pulsed.

The inverted signal of the X1 should be input to the X2.

Note that these pins are also pulsed during a read.

Operation mode selection pins during the write/verify cycles

8-bit data input/output pins during the write/verify cycles

Supply voltage

Normally 2.7 to 6 V; 6 V is applied during the write/verify cycles.

Cautions 1. The pins not used for write and verify should be processed as follows.

Port 0 - 2, Port 6, XT1

S0 - S9, T0 - T15

···· Connect to GND (directly connectable)

XT2 ·········································

Open

2. An opaque film should be placed over the UV erase window of the

µPD75P218KB except when

erasing the EPROM contents.

3. The

µPD75P218CW/GF does not have a UV erase window, thus the PROM contents cannot be

erased with ultraviolet ray.

4.1

PROM WRITE AND VERIFY OPERATION

verify mode. The operation is selected by the MD0 to MD3 pins, as shown in Table 4-2.

Table 4-2 PROM Write and Verify Operation Mode







Operation Mode

Clear program memory address to 0

Write mode

Verify mode

Program inhibit

Operation Mode Specification

MD0

MD1

MD2

MD3

+12.5 V

+6 V

H

L

H

L

L

HHH

LL

H

H

H

×

HH

×: Don’t care.