EM73PA88A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
EXAMPLE:
Operation
Carry Zero
8-4=4
7-F= -8(1000)
9-9=0
1
0
1
0
0
1
(3) Rotation:
Two types of rotation operation are available, one is rotation left, the other is rotation right.
RLCA instruction rotates Acc value counter-clockwise, shift the CF value into the LSB bit of Acc and hold
the shift out data in CF.
MSB LSB
ACC
CF
RRCA instruction operation rotates Acc value clockwise, shift the CF value into the MSB bit of Acc and
hold the shift out data in CF.
MSB LSB
ACC
CF
PROGRAM EXAMPLE: To rotate Acc clockwise (right) and shift a "1" into the MSB bit of Acc.
TTCFS; CF ← 1
RRCA; rotate Acc right and shift CF=1 into MSB.
HL REGISTER
HL register are two 4-bit registers, they are used as a pair of pointer for the RAM memoryaddress. They are
used as also 2 independent temporary 4-bit data registers. For certain instructions, L register can be a pointer
to indicate the pin number ( Port4 only ).
HL REGISTER STRUCTURE
3
2
1
0
3
2
1
0
L REGISTER
H REGISTER
HL REGISTER FUNCTION
(1)HL register is used as a temporary register for instructions : LDL #k, LDH #k, THA, THL, INCL, DECL,
EXAL, EXAH.
PROGRAM EXAMPLE: Load immediate data "5h" into L register, "0Dh" into H register.
LDL #05h;
LDH #0Dh;
(2) HL register is used as a pointer for the address of RAM memory for instructions : LDAM, STAM, STAMI ..,
PROGRAM EXAMPLE: Store immediate data "#0Ah" into RAM of address 35h.
* This specification are subject to be changed without notice.
10.8.2001
15
ELAN [ ELAN MICROELECTRONICS CORP ]
