4. A Quick Look at Design: How Processors Are Organized
The internal design of a processor, known as its architecture, determines how it handles instructions and data. Think of these designs as different blueprints for a kitchen. One blueprint might have a single pantry for all your food (ingredients and ready-to-eat meals), while another has two separate pantries—one for ingredients and one for meals—so the chef can grab both at the same time. Similarly, one philosophy for building a processor is to give it complex gadgets (like a food processor) that do a lot of work on their own (hardware). Another is to give it a few simple tools (like a knife and a cutting board) and rely on the chef’s skill (software) to make complex meals.
| Von Neumann Architecture | Harvard Architecture |
| Uses a single, shared memory and bus for both program instructions and data. | Uses separate storage and buses for program instructions and data, allowing simultaneous access. |
Another fundamental design choice is the type of instructions the processor can execute.
| CISC (Complex Instruction Set Computer) | RISC (Reduced Instruction Set Computer) |
| Uses a large number of complex instructions. | Uses a smaller set of simple instructions that execute faster. |
| Emphasis is on the hardware to perform tasks. | Emphasis is on the software to perform tasks. |
Let’s look at a real-world example that brings many of these concepts together.