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EM73983

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

ELAN Microelectronics 

EM73983

4-BIT MICRO-CONTROLLER FOR LCD PRODUCT

Preliminary

PROGRAM EXAMPLE:

Check following arithematic operation for CF, ZF, SF

LDIA #00h;

LDIA #03h;

ADDA #05h;

ADDA #0Dh;

ADDA #0Eh;

CF ZF

SF

-

1

1

-

0

1

-

0

1

-

0

0

-

0

0

ALU

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

the result of ALU operation, ZF and SF . The operation of ALU is affected by CF only .

ALU STRUCTURE

ALU supported user arithematic operation functions, including Addition, Subtraction and Rotaion.

DATA BUS

ALU

ALU FUNCTION

ZF CF SF

(1) Addition:

ALU supports addition function with instructions ADDAM, ADCAM, ADDM #k, ADD #k,y .... .

The addition operation affects CF and ZF. Under addition operation, if the result is "0", ZF will be "1",

otherwise, ZF will be "0", When the addition operation has a carry-out. CF will be "1", otherwise, CF will

be "0".

EXAMPLE:

Operation

3+4=7

7+F=6

0+0=0

8+8=0

Carry Zero

0

0

1

0

0

1

1

1

(2) Subtraction:

ALU supports subtraction function with instructions SUBM #k, SUBA #k, SBCAM, DECM... . The

subtraction operation affects CF and ZF, Under subtraction operation, if the result is negative, CF will

be "0", and 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 is "1", likewise, ZF is "1".

* This specification are subject to be changed without notice.

10.31.2000 11

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