Internal Program Memory Space - NEC UPD789026 Series User Manual

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 µ PD789026 Subseries provides the internal ROMs (or flash memory) containing the following capacities on
each product.
The following areas are allocated to the internal program memory space:
(1) Vector table area
A 44-byte area of addresses 0000H to 002BH is reserved as a vector table area. This area stores program
start addresses to be used when branching by the RESET input or an interrupt request generation. Of a 16-
bit program address, the low-order 8 bits are stored in an even address, and the high-order 8 bits are stored
in an odd address.
Vector Table Address
0000H
0004H
www.DataSheet4U.com
0006H
0008H
000AH
(2) CALLT instruction table area
In a 64-byte area of addresses 0040H to 007FH, the subroutine entry address of a 1-byte call instruction
(CALLT) can be stored.
46
CHAPTER 3 CPU ARCHITECTURE
Table 3-1. Internal ROM Capacity
Part Number
µ PD789022
µ PD789024
µ PD789025
µ PD789026
µ PD78F9026A
Table 3-2. Vector Table
Interrupt Request
RESET input
INTWDT
INTP0
INTP1
INTP2
User's Manual U11919EJ3V0UM00
Internal ROM
Structure Capacity
4,096 × 8 bits
Mask ROM
8,192 × 8 bits
12,288 × 8 bits
16,384 × 8 bits
16,384 × 8 bits
Flash memory
Vector Table Address
000CH
000EH
0010H
0014H
002AH
Interrupt Request
INTSR/INTCSI0
INTST
INTTM0
INTTM2
INTKR