EM73461A
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
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 (4K 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 4K - byte size ROM, PC can indicate address form 000h - FFFh, 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 a
SF=0; PC← PC +1( branch condition not satisified )
PC Original PC value + 1
a
a
a
a
LBR a
Object code: 1100 aaaa aaaa aaaa
Condition: SF=1; PC ← a ( branch condition satisified )
PC a
SF=0 ; PC ← PC + 2 ( branch condition not satisified )
PC Original PC value + 2
a
a
a
a
a
a
a
a
a
a
a
(2) Subroutine instruction:
SCALL a
Object code: 1110 nnnn
Condition : PC ← a ; a=8n+6 ; n=1..15 ; a=86h, n=0
PC 0
LCALL a
Object code: 0100 0 aaa aaaa aaaa
Condition: PC ← a
0
0
0
a
a
a
a
a
a
a
a
a
a
PC 0
a
a
a
a
a
a
a
a
a
* This specification are subject to be changed without notice.
1.5.2001
6
ELAN [ ELAN MICROELECTRONICS CORP ]
