CHAPTER 3 CPU ARCHITECTURE
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(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) Option byte area
A 5-byte area of 0080H to 0084H and 1080H to 1084H can be used as an option byte area. Set the option byte
at 0080H to 0084H when the boot swap is not used, and at 0080H to 0084H and 1080H to 1084H when the boot
swap is used. For details, see CHAPTER 26 OPTION BYTE.
(4) CALLF instruction entry area
The area 0800H to 0FFFH can perform a direct subroutine call with a 2-byte call instruction (CALLF).
(5) On-chip debug security ID setting area (
μPD78F0397D only)
A 10-byte area of 0085H to 008EH and 1085H to 108EH can be used as an on-chip debug security ID setting
area. Set the on-chip debug security ID of 10 bytes at 0085H to 008EH when the boot swap is not used and at
0085H to 008EH and 1085H to 108EH when the boot swap is used. For details, see CHAPTER 28 ON-CHIP
DEBUG FUNCTION (
μPD78F0397D ONLY).
3.1.2 Memory bank (
μPD78F0396, 78F0397, and 78F0397D only)
The 16 KB area 8000H to BFFFH is assigned to memory banks 0 to 3 in the
μPD78F0396, and assigned to
memory banks 0 to 5 in the
μPD78F0397 and 78F0397D.
The banks are selected by using a memory bank select register (BANK). For details, see CHAPTER 4 MEMORY
BANK SELECT FUNCTION (
μPD78F0396, 78F0397, AND 78F0397D ONLY)).
Cautions 1. Instructions cannot be fetched between different memory banks.
2. Branch and access cannot be directly executed between different memory banks. Execute
branch or access between different memory banks via the common area.
3. Allocate interrupt servicing in the common area.
4. An instruction that extends from 7FFFH to 8000H can only be executed in memory bank 0.
3.1.3 Internal data memory space
78K0/LG2 products incorporate the following RAMs.
(1) Internal high-speed RAM
Table 3-4. Internal High-Speed RAM Capacity
Part Number
Internal High-Speed RAM
μPD78F0393
μPD78F0394
μPD78F0395
μPD78F0396
μPD78F0397, 78F0397D
1024
× 8 bits (FB00H to FEFFH)
The 32-byte area FEE0H to FEFFH is assigned to four general-purpose register banks consisting of eight 8-bit
registers per bank.
This area cannot be used as a program area in which instructions are written and executed.
The internal high-speed RAM can also be used as a stack memory.
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