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CHAPTER 3 CPU ARCHITECTURE
Preliminary User’s Manual U16035EJ1V0UM
3.1.1 Internal program memory space
The internal program memory space contains the program and table data. Normally, it is addressed with the
program counter (PC).
The
µ
PD780024AS, 780034AS Subseries products incorporate an on-chip ROM (or flash memory), as listed below.
Table 3-1. Internal ROM Capacity
Part Number
Type
Capacity
µ
PD780021AS, 780031AS
Mask ROM
8192
×
8 bits (0000H to 1FFFH)
µ
PD780022AS, 780032AS
16384
×
8 bits (0000H to 3FFFH)
µ
PD780023AS, 780033AS
24576
×
8 bits (0000H to 5FFFH)
µ
PD780024AS, 780034AS
32768
×
8 bits (0000H to 7FFFH)
µ
PD78F0034BS
Flash memory
32768
×
8 bits (0000H to 7FFFH)
The internal program memory space is divided into the following three areas.
(1) Vector table area
The 64-byte area 0000H to 003FH is reserved as a vector table area. The RESET input and program start
addresses for branch upon generation of each interrupt request are stored in the vector table area. Of the 16-
bit address, lower 8 bits are stored at even addresses and higher 8 bits are stored at odd addresses.
Table 3-2. Vector Table
Vector Table Address
Interrupt Source
Vector Table Address
Interrupt Source
0000H
RESET input
0016H
INTCSI31
0004H
INTWDT
001AH
INTWTI
0006H
INTP0
001CH
INTTM00
0008H
INTP1
001EH
INTTM01
000AH
INTP2
0020H
INTTM50
000CH
INTP3
0022H
INTTM51
000EH
INTSER0
0024H
INTAD0
0010H
INTSR0
0026H
INTWT
0012H
INTST0
0028H
INTKR
0014H
INTCSI30
003EH
BRK
(2) CALLT instruction table area
The 64-byte area 0040H to 007FH can store the subroutine entry address of a 1-byte call instruction (CALLT).
(3) CALLF instruction entry area
The area 0800H to 0FFFH can perform a direct subroutine call with a 2-byte call instruction (CALLF).