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WESTERN DESIGN CENTER
W65C816S
March 1, 2000
19
SECTION 3
ADDRESSING MODES
The W65C816S is capable of directly addressing 16 MBytes of memory. This address space has special
significance within certain addressing modes, as follows:
3.1
Reset and Interrupt Vectors
The Reset and Interrupt Vectors use the majority of the fixed addresses between 00FFE0 and 00FFFF.
3.2
Stack
The Stack may be use memory from 000000 to 00FFFF. The effective address of Stack and Stack Relative addressing
modes will be always be within this range.
3.3
Direct
The Direct addressing modes are usually used to store memory registers and pointers. The effective address generated
by Direct, Direct,X and Direct,Y addressing modes is always in Bank 0 (000000-00FFFF).
3.4
Program Address Space
The Program Bank register is not affected by the Relative, Relative Long, Absolute, Absolute Indirect, and Absolute
Indexed Indirect addressing modes or by incrementing the Program Counter from FFFF. The only instructions that
affect the Program Bank register are: RTI, RTL, JML, JSL, and JMP Absolute Long. Program code may exceed 64K
bytes although code segments may not span bank boundaries.
3.5
Data Address Space
The Data Address space is contiguous throughout the 16 MByte address space. Words, arrays, records, or any data
structures may span 64 KByte bank boundaries with no compromise in code efficiency. The following addressing
modes generate 24-bit effective addresses:
Direct Indexed Indirect (d,x)
Direct Indirect Indexed (d),y
Direct Indirect (d)
Direct Indirect Long [d]
Direct Indirect Long Indexed [d],y
Absolute a
Absolute a,x
Absolute a,y
Absolute Long al
Absolute Long Indexed al,x
Stack Relative Indirect Indexed (d,x),y