NEC PD78078 Manuale Utente

569

CHAPTER 27

PD78P078, 78P078Y

The

PD78P078 and 78P078Y (PROM versions) replace the internal mask ROM of the mask ROM versions

(

PD78074, 78075, 78076, 78078, and

PD78074Y, 78075Y, 78076Y, 78078Y) with one-time programmable ROM

or EPROM, which enable program writing, erasure, and rewriting. Table 27-1 lists differences between the PROM

versions and mask ROM versions.

Table 27-1. Differences between PROM and Mask ROM Versions

Item

PD78P078, 78P078Y

Mask ROM Versions

Internal ROM format

One-time PROM/EPROM

Mask ROM

Internal ROM capacity

60 Kbytes

PD78076, 78076Y: 48 Kbytes

PD78078, 78078Y: 60 Kbytes

Changing internal ROM and internal high-speed RAM

Yes

Note 1

capacities by the internal memory size switching

Changing internal expansion RAM capacity by the

Yes

Note 2

internal expansion RAM size switching register (IXS)

IC pin

None

Available

None

P60 to P63 pins pull-up resistor internal mask option

None

Available

Electrical specifications

Refer to the data sheet of individual product

Notes 1. Internal PROM capacity becomes 60 Kbytes, and internal high-speed RAM capacity becomes 1024

bytes by RESET input.

2. Internal expansion RAM capacity becomes 1024 bytes by RESET input.

Caution There are differences in noise immunity and noise radiation between the PROM and mask ROM

versions. When pre-producing an application set with the PROM version and then mass-

producing it with the mask ROM version, be sure to conduct sufficient evaluations for the

consumer samples (not engineering samples) of the mask ROM version.