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4513/4514 Group User’s Manual
HARDWARE
1-17
FUNCTION BLOCK OPERATIONS
FUNCTION BLOCK OPERATIONS
CPU
(1) Arithmetic logic unit (ALU)
The arithmetic logic unit ALU performs 4-bit arithmetic such as 4-
bit data addition, comparison, AND operation, OR operation, and
bit manipulation.
(2) Register A and carry flag
Register A is a 4-bit register used for arithmetic, transfer, ex-
change, and I/O operation.
Carry flag CY is a 1-bit flag that is set to “1” when there is a carry
with the AMC instruction (Figure 1).
It is unchanged with both A n instruction and AM instruction. The
value of A0 is stored in carry flag CY with the RAR instruction (Fig-
ure 2).
Carry flag CY can be set to “1” with the SC instruction and cleared
to “0” with the RC instruction.
(3) Registers B and E
Register B is a 4-bit register used for temporary storage of 4-bit
data, and for 8-bit data transfer together with register A.
Register E is an 8-bit register. It can be used for 8-bit data transfer
with register B used as the high-order 4 bits and register A as the
low-order 4 bits (Figure 3).
(4) Register D
Register D is a 3-bit register.
It is used to store a 7-bit ROM address together with register A and
is used as a pointer within the specified page when the TABP p,
BLA p, or BMLA p instruction is executed (Figure 4).
Fig. 1 AMC instruction execution example
Fig. 2 RAR instruction execution example
Fig. 3 Registers A, B and register E
Fig. 4 TABP p instruction execution example
(CY)
(M(DP))
(A)
Addition
ALU
<Carry>
<Result>
CY A3 A2 A1 A0
A0 CY A3 A2 A1
<Rotation>
RAR instruction
<Set>
SC instruction
<Clear>
RC instruction
A3 A2 A1 A0B3 B2 B1 B0
E7 E6 E5 E4 E3 E2 E1 E0
A3 A2 A1 A0
B3 B2 B1 B0
TAB instruction
TEAB instruction
TABE instruction
TBA instruction
Register B Register A
Register B Register A
Register E
Specifying address
TABP p instruction
p6 p5 p4 p3 p2 p1 p0
PCH
DR2 DR1DR0
A3 A2 A1 A0
PCL
Immediate field
value p
The contents of
register D
ROM
840
Middle-order 4 bits
Low-order 4bits
Register A (4)
Register B (4)
The contents of
register A