User: Help me code a text based simulator for intel 4004 microprocessor in python. 
Assistant: Creating a text-based simulator for the Intel 4004 microprocessor in Python is a fun and educational project. The Intel 4004 is a 4-bit CPU, and working with it involves handling registers, a small addressable memory space, and instruction execution. Here, I'll guide you through setting up a basic simulation that supports a few instructions to get you started.

### Step 1: Define the CPU Structure

First, create a basic structure representing the CPU state, including registers and RAM.

```python
class Intel4004:
    def __init__(self):
        # Registers: 16 4-bit registers R0-R15
        self.registers = [0] * 16
        # Program Counter: 12-bit program counter
        self.pc = 0
        # Accumulator: 4-bit accumulator
        self.accumulator = 0
        # Carry flag
        self.carry_flag = 0
        # Memory: 4KB of ROM address space
        self.memory = [0] * 4096

    def load_program(self, program, start_address=0):
        """Load a program into memory starting at the given address."""
        for i, instruction in enumerate(program):
            self.memory[start_address + i] = instruction

    def fetch_instruction(self):
        """Fetch the next instruction from memory."""
        instruction = self.memory[self.pc]
        self.pc += 1
        return instruction

    def decode_execute(self, instruction):
        """Decode and execute the fetched instruction."""
        opcode = instruction >> 4  # Higher 4 bits
        operand = instruction & 0xF  # Lower 4 bits

        # Example of implementing a few basic instructions
        if opcode == 0x0:  # NOP
            pass
        elif opcode == 0x1:  # LDM Load immediate
            self.accumulator = operand
        elif opcode == 0x2:  # ADD
            result = self.accumulator + self.registers[operand] + self.carry_flag
            self.accumulator = result & 0xF
            self.carry_flag = (result >> 4) & 0x1
        elif opcode == 0x3:  # SUB
            result = self.accumulator - self.registers[operand] - self.carry_flag
            if result < 0:
                result += 16
                self.carry_flag = 1
            else:
                self.carry_flag = 0
            self.accumulator = result
        else:
            print(f"Unknown instruction: {hex(instruction)}")

    def run(self, start_address=0):
        """Run the program loaded into memory."""
        self.pc = start_address
        while True:
            instruction = self.fetch_instruction()
            if instruction is None:
                break  # End of program or invalid memory access
            self.decode_execute(instruction)
            self.debug_state()

    def debug_state(self):
        """Display the current state of the CPU for debugging."""
        print(f"PC: {self.pc:03} ACC: {self.accumulator:01X} "
              f"Carry: {self.carry_flag} Registers: {' '.join(f'{v:01X}' for v in self.registers)}")


# Example program and execution
program = [
    0x10,  # LDM 0
    0x21,  # ADD R1 (assuming R1 is 1)
    0x30,  # SUB R0 (assuming R0 is 0)
    0x00   # NOP or some form of halt instruction, end for simplification
]

cpu = Intel4004()
cpu.load_program(program, start_address=0)
cpu.run(start_address=0)
```

### Step 2: Expand Capabilities

The code provided implements a very basic simulator. To create a more complete simulator:

1. **Instruction Set Completeness**: Implement more of the 4004's instruction set, including jumps, logical operations, I/O commands, etc.
   
2. **Input/Output Simulation**: Implement methods for handling input and output ports.

3. **Testing and Debugging**: Run test programs to ensure the accuracy of the simulation, compare against expected results.

4. **Optimization and Cleanup**: Enhance the code for performance and use Python constructs effectively.

This simulator gives a foundation, and enhancing it will solidify your understanding of how the Intel 4004 operates. Happy coding!
User: here is the logic gates code i wrote :
def AND_Gate(a,b): 
    return a and b
def OR_Gate(a,b):
    return a or b
def NOT_Gate(a):
    return not a
def NAND_Gate(a,b):
    return not (a and b)
def NOR_Gate(a,b):
    return not a and not b
def XOR_Gate(a,b):
    return (a or b) and not (a and b)
def XNOR_Gate(a,b):
    return not ((a or b) and not (a and b))
- tell me how to use these to create a 4 bit register (for intel 4004 cpu).
Assistant: