RL78/G15 CHAPTER 3 CPU ARCHITECTURE
R01UH0959EJ0110 Rev.1.10 Page 69 of 765
Mar 7, 2023
3.3.3 ES and CS registers
The ES register and CS register are used to specify the higher address for data access and when a branch instruction is
executed (register indirect addressing), respectively.
The default value of the ES register after reset is 0FH, and that of the CS register is 00H.
Figure 3-8. Configuration of ES and CS Registers
Symbol 7 6 5 4 3 2 1 0
ES 0 0 0 0 ES3 ES2 ES1 ES0
Symbol 7 6 5 4 3 2 1 0
CS 0 0 0 0 CS3 CS2 CS1 CS0
Though the data area which can be accessed with 16-bit addresses is the 64 Kbytes from F0000H to FFFFFH, using the
ES register as well extends this to the 1 Mbyte from 00000H to FFFFFH.
Figure 3-9. Extension of Data Area Which Can Be Accessed
Special function register (SFR)
256 bytes
FFFFFH
00000H
F0000H
EFFFFH
!addr
16
!
addr16
→
F 0000
H to FFFFH
→
0H to
FH 0000H
to FFFFH
ES:!
addr16
Special function register (2nd SFR)
2 Kbytes
ES:!addr16
Data memory space
Code flash memory
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