UPD784915B Datasheet, PDF (19/86 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784915B, 784916B
3. INTERNAL BLOCK FUNCTIONS
3.1 CPU Registers
3.1.1 General-purpose registers
The µPD784916B has eight banks of general-purpose registers. One bank consists of sixteen 8-bit general-
purpose registers. Two of these 8-bit registers can be used in pairs as a 16-bit register. Four of the 16-bit general-
purpose registers can be used to specify a 24-bit address in combination with an 8-bit address expansion register.
These eight banks of general-purpose registers can be selected by software or context switching function.
The general-purpose registers, except for the address expansion registers V, U, T, and W, are mapped to the
internal RAM.
Figure 3-1. Configuration of General-Purpose Registers
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
UUP (RG5)
UP (RP5)
T
D (R13)
E (R12)
DE (RP6)
TDE (RG6)
W
H (R15)
L (R14)
HL (RP7)
WHL (RG7)
( ): absolute name
8 banks
Caution
Although 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 PSW to 1, do not use this function. The function of the
RSS bit is planned to be deleted from the future models in the 78K/IV Series.
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