NEC PD78078 用户手册

µ

7

RAM2

Symbol

IMS

6

RAM1

5

RAM0

4

0

3

ROM3

2

ROM2

1

ROM1

0

ROM0

Address

FFF0H

CFH

After

Reset

R/W

R/W

1

1

Internal ROM Capacity Selection

48 Kbytes

56 Kbytes

ROM3

60 Kbytes

1

1

1

ROM2

1

0

1

ROM1

1

0

0

ROM0

1

Setting prohibited

Other than above

Internal High-Speed RAM Capacity Selection

RAM2 RAM1 RAM0

1024 bytes

1

1

0

Setting prohibited

Other than above

The 

µ

PD78P078 and 78P078Y allow users to define its internal memory sizes using the internal memory size

switching register (IMS), so that the same memory mapping as that of a mask ROM version with a different-size

internal ROM is possible.

IMS is set with an 8-bit memory manipulation instruction.

RESET input sets IMS to CFH.

When using the external device extension function on the following devices, the internal ROM capacity

must be 56 Kbytes or less:

 

µ

PD78078, 78078Y, 78P078, 78P078Y.

µ

The IMS settings to give the same memory map as mask ROM versions are shown in Table 27-2.

Relevant Mask ROM Version

IMS Setting

µ

PD78076, 78076Y

CCH

µ

PD78078, 78078Y

CFH