General Computer System Model

Welcome to the second article in our series on building a 6502 processor simulation in C++. In this article, we’ll focus on the General Computer System Model, laying the groundwork for understanding how computers operate at a fundamental level.

Let’s begin by exploring the core functions of a computer system and its essential components. A computer is an electronic device designed to process data according to a set of instructions stored internally. It takes input, processes the data (performing both mathematical and logical operations), generates output, and stores the results for future use. In simple terms, a computer’s primary job is to transform raw data into meaningful information.

Understanding this basic flow is crucial as it forms the foundation of the processor simulation we will build together.

To accomplish this, a computer is divided into five basic units:

Input Unit

The input unit allows data to enter the system. It includes devices that enable you to feed data into the computer, like a keyboard, mouse, or even external drives. These devices take the data from the outside world and transfer it to the computer for processing.

Output Unit

The output unit provides a way for the computer to communicate the results of processing to the user. Devices like monitors, printers, or speakers fall into this category. After processing, the data is transformed into readable information and presented to the user through these output devices.

Central Processing Unit (CPU)

Often called the brain of the computer, the CPU is responsible for executing instructions. It has three main components:

• Arithmetic and Logic Unit (ALU): Handles all arithmetic (addition, subtraction, etc.) and logical operations (comparisons, decision making, etc.).
• Control Unit (CU): Manages and controls the operations of all other components by sending control signals.
• Registers: These are small, high-speed storage locations that temporarily hold data or instructions while they are being processed.

Memory Unit

The memory unit stores data and instructions either temporarily or permanently. It consists of two types:

• Primary Memory: This is the temporary storage that holds data and programs currently in use. Examples include RAM and cache memory.
• Secondary Memory: This provides long-term storage for data and programs, such as hard drives or USB drives.

Bus

The bus is like a data highway that connects all the components. It enables communication between the CPU, memory, and input/output devices. Think of it as a set of wires that transfer data between various parts of the computer.

What Comes Next: COA - Computer Bus

Now that you have an understanding of the overall computer system model, our next focus will be on the Computer Bus. The bus is a crucial element that ties all the components together and ensures data can flow efficiently between them. In the next article, we’ll explore how different types of buses work, how they manage data transfer, and why they are so important to the overall performance of a computer system.

Stay tuned as we break down the role of the computer bus in the system!