4250 查看數據表（PDF） - MITSUBISHI ELECTRIC

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4250

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

MITSUBISHI ELECTRIC  

MITSUBISHI MICROCOMPUTERS

4250 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

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 bit manipulation.

(2) Register A and carry flag

Register A is a 4-bit register used for arithmetic, transfer,

exchange, 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 (Figure 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).

(CY)

(M(DP))

Addition

<Carry>

ALU

(A)

<Result>

Fig. 1 AMC instruction execution example

<Set>

<Clear>

SC instruction RC instruction

CY

A3 A2 A1 A0

<Rotation>

RAR instruction

A0

CY A3 A2 A1

Fig. 2 RAR instruction execution example

Register B TAB instruction Register A

B3 B2 B1 B0

A3 A2 A1 A0

TEAB instruction

Register E E7 E6 E5 E4 E3 E2 E1 E0

TABE instruction

B3 B2 B1 B0

A3 A2 A1 A0

Register B TBA instruction Register A

Fig. 3 Registers A, B and register E

TABP p instruction

ROM

Specifying address

8

4

0

PCH

p3 p2 p1 p0

PCL

DR2 DR1 DR0 A3 A2 A1 A0

Immediate field The contents of The contents of

value p

register D

register A

Fig. 4 TABP p instruction execution example

Low-order 4 bits

Register A (4)

Middle-order 4 bits

Register B (4)

MITSUBISHI

ELECTRIC

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