6500 Registers

General Purpose Registers

1. A (Accumulator)

   • Used for arithmetic and logic operations.

   • Example:

     LDA #$10 ; Load immediate value 16 into A ADC #$05 ; Add 5 to A, result in A

2. X (Index Register X)

   • Used for indexing memory locations.

   • Example:

     LDX #$03 ; Load immediate value 3 into X LDA $2000,X ; Load value from address $2000 + X into A

3. Y (Index Register Y)

   • Used for indexing memory locations.

   • Example:

     LDY #$04 ; Load immediate value 4 into Y LDA $2000,Y ; Load value from address $2000 + Y into A

Stack Pointer

1. SP (Stack Pointer)

   • Points to the top of the stack.

   • Example:

     TSX ; Transfer SP to X

Program Counter

1. PC (Program Counter)

   • Points to the next instruction to be executed.

   • Example:

     JMP $3000 ; Jump to address $3000, PC is updated to $3000

Status Register

1. P (Processor Status)

   • Contains flags that reflect the outcome of operations and control the CPU.

   • Example:

     CLC ; Clear carry flag SEC ; Set carry flag

These registers are essential for various operations in 6500 assembly programming, providing the necessary functionality for arithmetic, data manipulation, control flow, and memory access.