User: i want to code a text based simulator for intel 4004 microprocessor . i have written some code , for example code for 7 logic gates is as follows :
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))
- i want you to help me complete this simulator , i dont know what to do next. or if intel 4004 circuit design is too complex can you recommend simpler deisgns ?
Assistant: Creating a text-based simulator for the Intel 4004 microprocessor is a challenging yet exciting project. The Intel 4004 is a complex CPU with several registers, an accumulator, and numerous instruction sets. Simulating an entire 4-bit microprocessor as a learning exercise is ambitious, but let's break it down step by step. If the 4004 seems too complex, you could start with a simpler processor or even design a custom, simplified CPU. I'll guide you through creating a basic simulator framework. Here’s how you can proceed:

### Key Components of the 4004

1. **Registers**: 
   - The Intel 4004 has 16 registers with a 4-bit width. These can be simulated using a list or dictionary.

2. **Accumulator (ACC)**:
   - A 4-bit register used for arithmetic operations.
   
3. **Program Counter (PC)**:
   - A 12-bit program counter that points to the next instruction to execute.
   
4. **Stack**:
   - A small call stack that helps in handling subroutine calls.
   
5. **Instruction Set**:
   - You will need to simulate the instruction set, notably operations like `ADD`, `SUB`, `JMP`, `CALL`, and so on.

### Building the Simulator

1. **Define Data Structures**:
   - Set up the memory, registers, and stack.

2. **Initialize CPU State**:
   - Define a class `CPU` with attributes for registers, accumulator, program counter, and stack.

3. **Instruction Execution**:
   - Create functions or methods within the CPU class to simulate behavior on instruction sets.

4. **Fetch-Decode-Execute Cycle**:
   - Implement the cycle that simulates how a CPU fetches, decodes, and executes instructions.

Below is a skeleton structure to help you get started:

```python
class Intel4004Simulator:
    def __init__(self):
        self.registers = [0] * 16  # 16 x 4-bit registers
        self.accumulator = 0  # 4-bit Accumulator
        self.pc = 0  # 12-bit program counter
        self.stack = []  # Simple list-based stack
        self.memory = [0] * 4096  # Assume a 4KB memory for demonstration

    def fetch(self):
        # Fetch the next instruction using the program counter
        instruction = self.memory[self.pc]
        self.pc += 1
        return instruction

    def decode_execute(self, instruction):
        # Decode and execute the instruction
        if instruction == 'NOP':
            pass  # No Operation
        elif instruction.startswith('ADD'):
            reg_num = int(instruction[3:])
            self.accumulator += self.registers[reg_num] & 0xF  # Ensure 4-bit result
        # Add more instruction handling here...

    def run(self):
        while self.pc < len(self.memory):
            instruction = self.fetch()
            self.decode_execute(instruction)

# Example logic gate functions can be reused or incorporated as needed.

# Initialize simulator
simulator = Intel4004Simulator()
# Load a simple example program sequence (hypothetical)
simulator.memory[0] = 'NOP'
simulator.memory[1] = 'ADD2'  # Hypothetical instruction

# Run the simulator
simulator.run()
```

### Considerations

1. **Simplified Models**: If the Intel 4004 is too complex, consider starting with an even simpler hypothetical 4-bit or 8-bit CPU design. 

2. **Learning Resources**:
   - Study computer architecture literature to understand CPU components and operations.
   - Look into emulation projects or simplified CPUs like the SAP-1 (Simple as Possible), which can be an easier start.

Approach the project incrementally—start by implementing basic operations and gradually add complexity. Document and test each part to ensure correctness. Good luck with your simulator!
User: modify the code to use the logic gates code i provided in order to make other parts.
Assistant: