UPD75518 NEC, UPD75518 Datasheet - Page 31

• Manufacturer Part Number: UPD75518
• Description: 4 BIT SINGLE-CHIP MICROCOMPUTER
• Manufacturer: NEC

Address
3.4 GENERAL REGISTERS: 8
provided, with each bank consisting of eight 4-bit registers (B, C, D, E, H, L, X, A).
for 8-bit manipulation. DL also makes a register pair as well as DE and HL; these three register pairs can be
used as data pointers.
as a register.
000H
001H
002H
003H
004H
005H
006H
007H
008H
00FH
010H
017H
018H
01FH
The general registers are mapped to particular addresses in data memory. Four banks of registers are
The register bank (RB) to be enabled at the time of instruction execution is determined by
RB = RBE•RBS: (RBS = 0 to 3)
Each general register allows 4-bit manipulation. In addition, BC, DE, HL, or XA serves as a register pair
A general register area can be addressed and accessed as normal RAM, regardless of whether it is used
3
Fig. 3-4 General Register Format
Same as bank 0
Same as bank 0
Same as bank 0
A register
H register
D register
C register
B register
X register
L register
E register
Data memory
0
4 BITS
Register bank 0
Register bank 1
Register bank 2
Register bank 3
4 BANKS
3
3
3
3
Fig. 3-5 Register Pair Format
D
H
B
X
0
0
0
0
3
3
3
3
PD75518(A)
C
E
A
L
31
0
0
0
0