Prom Programming; Operating Modes; Prom Programming Operating Modes - NEC PD78081(A) User Manual

15.2 PROM Programming

The PD78P083 incorporate a 24-Kbyte PROM as program memory, respectively. To write a program into
the PD78P083 PROM, make the device enter the PROM programming mode by setting the levels of the V
and RESET pins as specified. For the connection of unused pins, see paragraph (2) "PROM programming
mode" in section 1.5 Pin Configuration (Top View).
Caution Perform program writing only in the 0000H to 5FFFH address range (specify the last address
as 5FFFH.)
The program cannot be correctly written by a PROM programmer which does not have a write
address specification function.

15.2.1 Operating modes

When +5 V or +12.5 V is applied to the V
are set to the PROM programming mode. This is one of the operating modes shown in Table 15-3 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
Remark : L or H
(1) Read mode
Read mode is set by setting CE to L and OE to L.
(2) Output disable mode
If OE is set to H, data output becomes high impedance and the output disable mode is set.
Therefore, if multiple PD78P083s are connected to the data bus, data can be read from any one device by
controlling the OE pin.
CHAPTER 15
pin and a low-level signal is applied to the RESET pin, the PD78P083
PP
Table 15-3. PROM Programming Operating Modes
Pin
RESET V
PP
L +12.5 V
+5 V
PD78P083
V CE OE
DD
+6.5 V H L
H H
L H
L L
H
L
+5V L L
L H
H
PGM D0-D7
H Data input
L High impedance
L Data input
H Data output
H High impedance
L
H Data output
High impedance
High impedance
PP
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