GMS81C50 Datasheet, PDF (33/99 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCONTROLLERS

GMS81C50 Series
HYUNDAI
8.4 Addressing Mode
The GMS81C50 Series uses six addressing modes;
• Register addressing
• Immediate addressing
• Direct page addressing
• Absolute addressing
• Indexed addressing
• Register-indirect addressing
(1) Register Addressing
Register addressing accesses the A, X, Y, C and PSW.
(2) Immediate Addressing → #imm
In this mode, second byte (operand) is accessed as a data
immediately.
Example:
0435 ADC #35H
MEMORY
04
A+35H+C → A
35
When G-flag is 1, then RAM address is difined by 16-bit
address which is composed of 8-bit RAM paging register
(RPR) and 8-bit immediate data.
Example: G=1, RPR=0CH
E45535 LDM 35H,#55H
0C35_H
data
~~
–
0F100_H
E4
0F101_H
55
0F102H
35
data ← 55H
~~
—
(3) Direct Page Addressing → dp
In this mode, a address is specified within direct page.
Example; G=0
C535 LDA 35H
;A ←RAM[35H]
35H
data
~~
0E550H
C5
0E551_H
35
—
~~ _– data → A
(4) Absolute Addressing → !abs
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.
With 3 bytes command, it is possible to access to whole
memory area.
ADC, AND, CMP, CMPX, CMPY, EOR, LDA, LDX,
LDY, OR, SBC, STA, STX, STY
Example;
0735F0 ADC !0F035H
;A ←ROM[0F035H]
0F035_H
~~
0F100H
0F101_H
0F102_H
data
07
35
F0
—
~~
A+data+C → A
–
address: 0F035
30