NEC NEC PD78081(A), User Manual

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CHAPTER 3 CPU ARCHITECTURE
3.1.1 Internal program memory space
The internal program memory is mask ROM with a 8192
×
8-bit configuration in the
µ
PD78081, and a 16384
×
8-bit configuration in the
µ
PD78082, and PROM with a 24576
×
8-bit configuration in the
µ
PD78P083.
The internal program memory space stores programs and table data. Normally, they are addressed with a program
counter (PC).
The internal program memory 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, low-order 8 bits are stored at even addresses and high-order 8 bits are stored at odd addresses.
Table 3-1. Vector Table
Vector Table Address Interrupt Request
0000H RESET input
0004H INTWDT
0008H INTP1
000AH INTP2
000CH INTP3
0018H INTSER
001AH INTSR/INTCSI2
001CH INTST
0028H INTAD
002AH INTTM5
002CH INTTM6
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).