w65c816s Western Design Center, Inc., w65c816s Datasheet - Page 17

• Manufacturer Part Number: w65c816s
• Description: W65c816s 8/16?bit Microprocessor
• Manufacturer: Western Design Center, Inc.

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
The Reset and Interrupt Vectors use the majority of the fixed addresses between 00FFE0 and 00FFFF.
3.2
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
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
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
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:
The following addressing mode descriptions provide additional detail as to how effective addresses are
calculated. Twenty-four addressing modes are available for the W65C816S.
Reset and Interrupt Vectors
Stack
Direct
Program Address Space
Data Address Space
Absolute a
Absolute a,x
Absolute a,y
Absolute Long al
Absolute Long Indexed al,x
Direct Indexed Indirect (d,x)
Direct Indirect (d)
Direct Indirect Indexed (d),y
Direct Indirect Long [d]
Direct Indirect Long Indexed [d],y
Stack Relative Indirect Indexed (d,x),y
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