9

* This specification are subject to be changed without notice.

EM73469A

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

1.9.2001

Preliminary

CF

ZF

SF

LDIA #00h;

-

1

1

LDIA #03h;

-

0

1

ADDA #05h;

-

0

1

ADDA #0Dh;

-

0

0

ADDA #0Eh;

-

0

0

ALU

The arithematic operation of 4 - bit data is performed in ALU unit. There are 2 flags can be affected by the

result of ALU operation, ZF and SF. The operation of ALU can be affected by CF only.

ALU STRUCTURE

ALU supported user arithematic operation function, including : addition, subtraction and rotaion.

ALU FUNCTION

(1) Addition:

For instruction ADDAM, ADCAM, ADDM #k, ADD #k,y .... ALU supports addition function.

The addition operation can affect CF and ZF. For addition operation, if the result is "0", ZF will be "1",

otherwise, not equal "0", ZF will be "0". When the addition operation has a carry-out, CF will be "1",

otherwise, CF will be "0".

EXAMPLE:

Operation

Carry

Zero

3+4=7

0

0

7+F=6

1

0

0+0=0

0

1

8+8=0

1

1

(2) Subtraction:

For instruction SUBM #k, SUBA #k, SBCAM, DECM... ALU supports user subtraction function. The

subtraction operation can affect CF and ZF, For subtraction operation, if the result is negative, CF will

be "0", it means a borrow out, otherwise, if the result is positive, CF will be "1". For ZF, if the result of

subtraction operation is "0", the ZF will be "1", otherwise, ZF will be "1".

ZF CF

SF GF

ALU

DATA BUS