UPD78P014 datasheet(18/62 Pages) NEC

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µPD78P014

INTERNAL MEMORY SIZE SWITCHING REGISTER (IMS)

This register is used to prevent part of the internal memory from being used by software. Setting the internal

memory size switching register (IMS) enables memory mapping identical to that of a mask ROM version with

different internal memory (ROM and RAM) to be used.

The IMS register is set by an 8-bit memory manipulation instruction.

RESET input sets this register to C8H.

Figure 3-1. Internal Memory Size Switching Register Format

Address

At Reset

R/W

FFF0H

C8H

IMS

RAM2 RAM1 RAM0

ROM3 ROM2 ROM1 ROM0

The IMS set values to make the memory map identical to various mask ROM versions are shown in Table 3-1.

Table 3-1. Examples of Internal Memory Size Switching Register Settings

IMS Set Value

Target Mask ROM Version

IMS Set Value

Target Mask ROM Version

µPD78001B

µPD78002B

µPD78011B

ROM3 ROM2 ROM1 ROM0

Internal ROM Capacity Selection

4 K bytes

8 K bytes

16 K bytes

24 K bytes

32K bytes

Setting prohibited

RAM2 RAM1 RAM0

Internal High-Speed RAM Capacity Selec-

tion

768 bytes

640 bytes

512 bytes

384 bytes

256 bytes

Setting prohibited

1024 bytes

896 bytes

Other than above

44H

C6H

C8H

µPD78012B

µPD78013

µPD78014

82H

64H

42H

UPD78P014 Datasheet(PDF) 18 Page - NEC

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