NEC PD78F9488 Manuale Utente

CHAPTER 3 CPU ARCHITECTURE

User’s Manual U15331EJ4V1UD

3.1.1 Internal program memory space

The internal program memory space stores programs and table data. This space is usually addressed by the

program counter (PC).

The

PD789489 Subseries provide internal ROM (or flash memory) with the following capacity for each product.

Table 3-1. Internal ROM Capacity

Part Number

Internal ROM

Structure

Capacity

PD789488 Mask

ROM

PD78F9488 Flash

memory

32768

× 8 bits

PD789489 Mask

ROM

PD78F9489 Flash

memory

49152

× 8 bits

The following areas are allocated to the internal program memory space.

(1) Vector table area

The 46-byte area of addresses 0000H to 002DH is reserved in the

PD789488 and 78F9488, and the 48-

byte area of address 0000H to 002FH is reserved in the

µPD789489 and 78F9489 as a vector table area.

This area stores program start addresses to be used when branching by RESET input or interrupt request
generation. Of a 16-bit program address, the lower 8 bits are stored in an even address, and the higher 8
bits are stored in an odd address.

Table 3-2. Vector Table

Vector Table Address

Interrupt Request

Vector Table Address

Interrupt Request

0000H RESET

input

0018H INTTM20

0004H INTWDT

001AH INTTM50

0006H INTP0 001CH INTTM60

0008H INTP1 001EH INTTM61

000AH INTP2 0020H INTAD0

000CH INTP3 0022H INTWT

000EH INTRIN

Note

0024H

INTKR00

0010H INTSR20/INTCSI20

0026H INTRERR

Note

0012H INTCSI10

0028H INTGP

Note

0014H INTST20

002AH INTREND

Note

0016H INTWTI 002CH INTDFULL

Note

002EH

INTKR01

Note

PD789489 and 78F9489 only. There are no interrupt requests corresponding to vector table

addresses 000EH, and 0026H through 002EH for

PD789488 and 78F9488.

(2) CALLT instruction table area

The subroutine entry address of a 1-byte call instruction (CALLT) can be stored in the 64-byte area of
addresses 0040H to 007FH.