EM73362
4-BIT MICRO-CONTROLLER FOR LCD PRODUCT
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
LCD DISPLAY RAM
RAM address from 40h ~ 46h, 50h ~ 56h, 60h ~ 66h are LCD display RAM, the RAM data of this region can't
be operated by instruction “LDHL xx” and “EXHL”.
Address Increment
bit 0 1 2 3 0 1 2
40h~46h (COM0)
50h~56h (COM1)
60h~66h (COM2)
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 instructions,
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
a
a
a
a
a
a
a
a
a
a
a
* This specification are subject to be changed without notice.
6
10.8.2001
ELAN [ ELAN MICROELECTRONICS CORP ]
