6800 Registers

General Purpose Registers

1. A (Accumulator)

   • Used for arithmetic and logic operations.

   • Example:

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

2. B (Accumulator)

   • Used for arithmetic and logic operations.

   • Example:

     LDB #$20 ; Load immediate value 32 into B SUB #$05 ; Subtract 5 from B, result in B

Index Register

1. X (Index Register)

   • Used for indexing memory locations.

   • Example:

     LDX #$1000 ; Load immediate value 4096 into X LDA $2000,X ; Load value from address $2000 + X 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

Condition Code Register

1. CCR (Condition Code Register)

   • 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 6800 assembly programming, providing the necessary functionality for arithmetic, data manipulation, control flow, and memory access.