HMS81C2012A Datasheet, PDF (36/107 Pages) List of Unclassifed Manufacturers – CMOS Single-Chip 8-Bit Microcontroller with A/D Converter & VFD Driver

HMS81C2012A/2020A
8.4 Addressing Mode
The GMS800 series MCU 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 defined by 16-bit
address which is composed of 8-bit RAM paging register
(RPR) and 8-bit immediate data.
Example: G=1
E45535 LDM 35H,#55H
0135H
data
~~
➊
0F100H
E4
0F101H
55
0F102H
35
data ¨ 55H
~~
➋
(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
0E551H
35
➋
~~ _➊ 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]
0F035H
data
~~
0F100H
07
0F101H
35
0F102H
F0
➋
~~ _{➊ A+data+C → A}
address: 0F035
The operation within data memory (RAM)
ASL, BIT, DEC, INC, LSR, ROL, ROR
Example; Addressing accesses the address 0135_H regard-
less of G-flag.
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SEP. 2004 Ver 2.00