CHAPTER 4 CPU ARCHITECTURE
User’s Manual U14826EJ5V0UD
41
4.1.1 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
PD789860, 789861 Subseries provide the following internal ROMs (or EEPROM) containing the following
capacities.
Table 4-1. Internal ROM Capacity
Internal ROM
Part Number
Structure Capacity
µ
PD789860, 789861
Mask ROM
µ
PD78E9860A, 78E9861A
EEPROM
4,096
×
8 bits
The following areas are allocated to the internal program memory space:
(1) Vector table area
The 14-byte area of addresses 0000H to 000DH is reserved 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 address, the lower 8 bits are stored in an even address, and the higher 8 bits are stored in an odd
address.
Table 4-2. Vector Table
Vector Table Address
Interrupt Request
Vector Table Address
Interrupt Request
0000H RESET
input
0008H INTTM40
0002H INTKR1
000AH INTLVI1
0004H INTWDT
000CH INTEE0
0006H INTTM30
(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.
4.1.2 Internal data memory space
The
µ
PD789860, 789861 Subseries provide the following RAMs.
(1) Internal high-speed RAM
The internal high-speed RAM is provided in the area of FE80H to FEFFH.
The internal high-speed RAM can also be used as a stack memory.
(2) EEPROM
The EEPROM is provided in the area of F800H to F81FH.
For details of EEPROM, see
CHAPTER 5 EEPROM (DATA MEMORY)
.
Содержание PD789860
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