HYUNDAI MicroElectronics
GMS82512/16/24
(4) Absolute Addressing
!abs
→
ADC, AND, CMP, EOR, LDA, OR, SBC, STA, XMA
Example; X=15H, G=1
Absolute addressing sets corresponding memory data to
Data, i.e. second byte (Operand I) of command becomes
lower level address and third byte (Operand II) becomes
upper level address.
D4
LDA
{X}
;ACC←RAM[X].
With 3 bytes command, it is possible to access to whole
memory area.
115H
data
➋
ADC, AND, CMP, CMPX, CMPY, EOR, LDA, LDX,
LDY, OR, SBC, STA, STX, STY
data → A
~
~
~
~
➊
Example;
D4
0E550H
0735F0 ADC
!0F035H
;A ←ROM[0F035H]
data
0F035H
➋
X indexed direct page, auto increment {X}+
→
~
~
~
~
A+data+C → A
In this mode, a address is specified within direct page by
the X register and the content of X is increased by 1.
➊
0F100H
0F101H
0F102H
07
35
F0
address: 0F035
LDA, STA
Example; G=0, X=35H
DB
LDA
{X}+
The operation within data memory (RAM)
ASL, BIT, DEC, INC, LSR, ROL, ROR
Example; Addressing accesses the address 0135H regard-
less of G-flag.
35H
data
➋
data Æ A
36H Æ X
~
~
~
~
983501 INC
!0135H
;A ←ROM[135H]
➊
DB
135H
data
➌
➋
~
~
~
~
data+1 → data
0F100H
0F101H
0F102H
98
35
01
➊
X indexed direct page (8 bit offset)
dp+X
→
address: 0135
This address value is the second byte (Operand) of com-
mand plus the data of ꢀ-register. And it assigns the mem-
ory in Direct page.
ADC, AND, CMP, EOR, LDA, LDY, OR, SBC, STA
STY, XMA, ASL, DEC, INC, LSR, ROL, ROR
(5) Indexed Addressing
X indexed direct page (no offset)
Example; G=0, X=0F5H
{X}
→
In this mode, a address is specified by the X register.
FEB. 2000 Ver 1.00
25
HYNIX [ HYNIX SEMICONDUCTOR ]
