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CHAPTER 3 CPU ARCHITECTURE
User’s Manual U12697EJ3V0UM
WHL (RG7):
•
This register primarily performs 24-bit data transfers and operation processing.
•
This register functions as a pointer and specifies the base address during register indirect addressing or based
addressing.
•
This functions as a pointer in string and SACW instructions.
In addition to its function name (X, A, C, B, E, D, L, H, AX, BC, VP, UP, DE, HL, VVP, UUP, TDE, WHL) that
emphasizes its unique function, each register can be described by its absolute name (R0 to R15, RP0 to RP7, RG4
to RG7). For the correspondence, refer to
Table 3-5
.
Table 3-5. Correspondence Between Function Names and Absolute Names
(a) 8-bit registers
Absolute Name
Function Name
RSS = 0
RSS = 1
Note
R0
X
R1
A
R2
C
R3
B
R4
X
R5
A
R6
C
R7
B
R8
R9
R10
R11
R12
E
E
R13
D
D
R14
L
L
R15
H
H
Note
Use RSS = 1 only when a 78K/III Series program is used.
Remark
R8 to R11 do not have function names.
(b) 16-bit registers
Absolute Name
Function Name
RSS = 0
RSS = 1
Note
RP0
AX
RP1
BC
RP2
AX
RP3
BC
RP4
VP
VP
RP5
UP
UP
RP6
DE
DE
RP7
HL
HL
(c) 24-bit registers
Absolute Name
Function Name
RG4
VVP
RG5
UUP
RG6
TDE
RG7
WHL
