UPD178024GC datasheet(17/56 Pages) NEC

17 / 56 page

µPD178023, 178024

Data Sheet U14126EJ1V0DS00

2.1 Memory Size Select Register (IMS)

The memory size select register (IMS) sets the internal memory capacity.

Set the

µPD178023, µPD178024 to C6H, C8H respectively.

Use an 8-bit memory manipulation instruction to set the IMS.

This register is set to CFH at reset.

Caution Be sure to set the IMS to C6H or C8H as the program initial setting. The IMS set value changes

to CFH when reset. Therefore, set C6H or C8H again after reset.

Figure 2-2. Format of Memory Size Select Register (IMS)

RAM2

RAM1

RAM0

Selects Internal High-speed RAM Capacity

1024 bytes

Others

Setting prohibited

RAM3

RAM2

RAM1

RAM0

Selects Internal ROM Capacity

0110

24K bytes

1000

32K bytes

Others

Setting prohibited

Table 2-1 indicates the setting of IMS.

Table 2-1. Set Value of Memory Size Select Register (IMS)

Targeted Model

Set Value of IMS

µPD178023

C6H

µPD178024

C8H

RAM2

RAM1

RAM0

ROM3

ROM2

ROM1

ROM0

Symbol

IMS

At reset

CFH

R/W

Address

FFF0H

UPD178024GC Datasheet(PDF) 17 Page - NEC

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