W65C816S Datasheet, PDF (20/62 Pages) List of Unclassifed Manufacturers – Microprocessor

The Western Design Center, Inc.
4 ADDRESSING MODES
W65C816S Data Sheet
The W65C816S is capable of directly addressing 16 MBytes of memory. This address space has special
significance within certain addressing modes, as follows:
4.1 Reset and Interrupt Vectors
The Reset and Interrupt Vectors use the majority of the fixed addresses between 00FFE0 and 00FFFF.
4.2 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.
4.3 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).
4.4 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.
4.5 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:
• 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
The following addressing mode descriptions provide additional detail as to how effective addresses are
calculated. Twenty-four addressing modes are available for the W65C816S.
The Western Design Center
W65C816S
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