UPD78F0138 NEC, UPD78F0138 Datasheet - Page 72

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

3.2.2 General-purpose registers
general-purpose registers consists of 4 banks, each bank consisting of eight 8-bit registers (X, A, C, B, E, D, L, and H).
(AX, BC, DE, and HL).
absolute names (R0 to R7 and RP0 to RP3).
the 4-register bank configuration, an efficient program can be created by switching between a register for normal
processing and a register for interrupts for each bank.
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General-purpose registers are mapped at particular addresses (FEE0H to FEFFH) of the data memory. The
Each register can be used as an 8-bit register, and two 8-bit registers can also be used in a pair as a 16-bit register
These registers can be described in terms of function names (X, A, C, B, E, D, L, H, AX, BC, DE, and HL) and
Register banks to be used for instruction execution are set by the CPU control instruction (SEL RBn). Because of
FEFFH
FEF8H
FEF0H
FEE8H
FEE0H
FEFFH
FEF8H
FEF0H
FEE8H
FEE0H
BANK0
BANK1
BANK2
BANK3
BANK0
BANK1
BANK2
BANK3
Figure 3-22. Configuration of General-Purpose Registers
CHAPTER 3 CPU ARCHITECTURE
User’s Manual U16228EJ2V0UD
(a) Absolute name
(b) Function name
15
15
16-bit processing
16-bit processing
RP3
RP2
RP1
RP0
DE
BC
HL
AX
0
0
7
7
8-bit processing
8-bit processing
R7
R6
R5
R4
R3
R2
R1
R0
H
D
E
B
C
A
X
L
0
0