How do branch instructions work?

How do branch instructions work?

1. A branch is an instruction in a computer program that can cause a computer to begin executing a different instruction sequence and thus deviate from its default behavior of executing instructions in order.
2. Mechanically, a branch instruction can change the program counter (PC) of a CPU.

What are different branch instructions?

Branching instructions refer to the act of switching execution to a different instruction sequence as a result of executing a branch instruction. The three types of branching instructions are: Jump (unconditional and conditional) Call (unconditional and conditional) Return (unconditional and conditional)

Which register is affected by a branch instruction?

the status register
In most instruction sets branch instructions are performed based on flags on the status register.

How do I find my branch address?

A branch instruction computes the target address in one of four ways:

1. Target address is the sum of a constant and the address of the branch instruction itself.
2. Target address is the absolute address given as an operand to the instruction.
3. Target address is the address found in the Link Register.

How does the 2 cycle branch work in the 6502?

The 6502 has a two-stage “pipeline” for instruction decoding, so the opcode for the next is already fetched in the last cycle of the current instruction. This is how the 2 cycle variant of branch works: One cycle for opcode fetch, one cycle to fetch the offset, and if the branch is not taken, then the next opcode is just fetched normally.

How does the MOS 6502 implement its branch?

Enter a branch, and watch what the control lines do. You can even see where every signal is located on the chip. The 6502 has a two-stage “pipeline” for instruction decoding, so the opcode for the next is already fetched in the last cycle of the current instruction.

What is the address of the 6502 instruction?

6502 instruction operation codes (opcodes) are eight-bits long and have the general form AAABBBCC, where AAA and CC define the opcode, and BBB defines the addressing mode. [70] For instance, consider the ORA instruction, which performs a bitwise OR on the bits in the accumulator with another value.

How does a 6502 assembly language statement work?

A 6502 assembly language statement consists of a three-character instruction mnemonic, followed by any operands. Instructions that do not take a separate operand but target a single register based on the addressing mode combine the target register in the instruction mnemonic, so the assembler uses INX as opposed to INC X to increment the X