NEC mPD75512 Datasheet page 37

(2) Legend of operation field
A : A register; 4-bit accumulator
B : B register; 4-bit accumulator
C : C register; 4-bit accumulator
D : D register; 4-bit accumulator
E : E register; 4-bit accumulator
H : H register; 4-bit accumulator
L : L register; 4-bit accumulator
X : X register; 4-bit accumulator
XA : Register pair (XA); 8-bit accumulator
BC : Register pair (BC); 8-bit accumulator
DE : Register pair (DE); 8-bit accumulator
HL : Register pair (HL); 8-bit accumulator
XA' : Expanded register pair (XA')
BC' : Expanded register pair (BC')
DE' : Expanded register pair (DE')
HL' : Expanded register pair (HL')
PC : Program counter
SP : Stack pointer
CY : Carry flag; or bit accumulator
PSW : Program status word
MBE : Memory bank enable flag
RBE : Register bank enable flag
PORTn : Port n (n = 0 to 15)
IME : Interrupt mask enable flag
IPS : Interrupt priority selector register
IExxx : Interrupt enable flag
RBS : Memory bank selector register
MBS : Memory bank selector register
PCC : Processor clock control register
.
: Delimiter of address and bit
(xx) : Contents addressed by xx
xxH : Hexadecimal data
µ PD75512
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