UPD784044 Datasheet, PDF (21/90 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784044(A), 784046(A)
6.2 CPU Registers
6.2.1 General-purpose registers
Sixteen 8-bit general-purpose registers are provided. Two 8-bit general-purpose registers can be used in
pairs as a 16-bit general-purpose register. Of the 16-bit registers, four can be used with an 8-bit register for
address expansion as 24-bit address specification registers.
Eight banks of register sets are available which can be selected by software or context switching function.
The general-purpose registers except the V, U, T, and W registers for address expansion are mapped to the
internal RAM.
Figure 6-3. General-Purpose Register Format
A(R1)
X(R0)
AX(RP0)
B(R3)
C(R2)
BC(RP1)
R5
R4
RP2
R7
R6
RP3
V
R9
R8
VP(RP4)
VVP(RG4)
U
R11
R10
UP(RP5)
UUP(RG5)
T
D(R13)
E(R12)
DE(RP6)
TDE(RG6)
W
H(R15)
L(R14)
HL(RP7)
WHL(RG7)
( ): absolute name
8 banks
Caution
R4, R5, R6, R7, RP2, and RP3 can be used as X, A, C, B, AX, and BC registers, respectively, by
setting the RSS bit of the PSW to 1. However, use this function only when using a 78K/III series
program.
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