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19.3 PROM Programming
The µ PD78P0208 incorporates a 60 KB PROM as program memory. When programming, the PROM
programming mode is set by means of the V
to 1.5 Pin Configuration (Top View) (2) PROM programming mode.
Caution
Programs must be written in addresses 0000H to EFFFH (the last address EFFFH must be
specified). Programs cannot be written by a PROM programmer that cannot specify the write
address.
19.3.1 Operating modes
When +5 V or +12.5 V is applied to the V
µ PD78P0208 is set to the PROM programming mode. This is one of the operating modes shown in Table 19-
4 below according to the setting of the CE, OE, and PGM pins.
The PROM contents can be read by setting the read mode.
Operating Mode
Page data latch
Page write
Byte write
Program verify
Program inhibit
Read
Output disabled
Standby
×: L or H
(1) Read mode
Read mode is set by setting CE to L and OE to L.
(2) Output disabled mode
If OE is set to H, data output becomes high impedance and the output disabled mode is set.
Therefore, if multiple µ PD78P0208s are connected to the data bus, data can be read from any one device
by controlling the OE pin.
(3) Standby mode
Setting CE to H sets the standby mode.
In this mode, data output becomes high impedance irrespective of the status of OE.
CHAPTER 19 µ PD78P0208
pin and the RESET pin. For the connection of unused pins, refer
PP
pin and a low-level signal is applied to the RESET pin, the
PP
Table 19-4. PROM Programming Operating Modes
Pin RESET
V
V
PP
DD
L
+12.5 V
+6.5 V
+5 V
+5 V
User's Manual U11302EJ4V0UM
CE
OE
PGM
H
L
H
Data input
H
H
L
High impedance
L
H
L
Data input
L
L
H
Data output
×
H
H
High impedance
×
L
L
L
L
H
Data output
×
L
H
High impedance
×
×
H
High impedance
D0 to D7
375
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