EM73P461A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
CF
-
-
-
-
ZF
1
0
0
0
SF
1
1
1
0
LDIA #00h;
LDIA #03h;
ADDA #05h;
ADDA #0Dh;
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.
DATA BUS
ALU
ZF CF SF GF
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
7+F=6
0+0=0
8+8=0
0
1
0
1
0
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".
* This specification are subject to be changed without notice.
12.27.2001
13
ELAN [ ELAN MICROELECTRONICS CORP ]
