EM73P361A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
When user using any instruction of CALL or subroutine, before entry the subroutine, the previous PC address
will be saved into stack until return from those subroutines, the PC value will be restored by the data saved
in stack.
DATA AREA:
Except the special area used by user, the whole RAM can be used as data area for storing and loading general
data.
ADDRESSING MODE
(1) Indirect addressing mode:
Indirect addressing mode indicates the RAM address by specified HL register.
For example: LDAM ; Acc ← RAM[HL]
STAM ; RAM[HL] ← Acc
(2) Direct addressing mode:
Direct addressing mode indicates the RAM address by immediate data.
For example: LDA x ; Acc← RAM[x]
STA x ; RAM[x] ← Acc
(3) Zero-page addressing mode
For zero-page region, user can using direct addressing to write or do any arithematic, comparsion or bit
manupulated operation directly.
For example: STD #k,y ; RAM[y] ← #k
ADD #k,y; RAM[y] ← RAM[y] + #k
PROGRAM COUNTER (3K ROM)
Program counter ( PC ) is composed by a 12-bit counter, which indicates the next executed address for the
instruction of program ROM.
For a 3K - byte size ROM, PC can indicate address form 000h - BFFh, for BRANCH and CALL instrcutions,
PC is changed by instruction indicating.
(1) Branch instruction:
SBR a
Object code: 00aa aaaa
Condition: SF=1; PC ← PC 11-6.a ( branch condition satisified )
PC Hold original PC value+1 a
SF=0; PC← PC +1( branch condition not satisified)
PC Original PC value + 1
a
a
a
a
a
LBR a
Object code: 1100 aaaa aaaa aaaa
Condition: SF=1; PC ← a ( branch condition satisified)
PC a
a
a
a
a
a
a
a
a
a
a
a
* This specification are subject to be changed without notice.
12.17.2001
7
ELAN [ ELAN MICROELECTRONICS CORP ]
