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CHAPTER 27
µ
PD78P078, 78P078Y
The
µ
PD78P078 and 78P078Y (PROM versions) replace the internal mask ROM of the mask ROM versions
(
µ
PD78074, 78075, 78076, 78078, and
µ
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
µ
PD78P078, 78P078Y Mask ROM Versions
Internal ROM format One-time PROM/EPROM Mask ROM
Internal ROM capacity 60 Kbytes
µ
PD78076, 78076Y: 48 Kbytes
µ
PD78078, 78078Y: 60 Kbytes
Changing internal ROM and internal high-speed RAM Yes
Note 1
No
capacities by the internal memory size switching
register (IMS)
Changing internal expansion RAM capacity by the Yes
Note 2
No
internal expansion RAM size switching register (IXS)
IC pin None Available
VPP pin 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.