Computer architecture is the practice of designing and constructing computers. The design is quite abstract and it describes how something should work internally. Construction pertains to the handling of physical components. We can construct different computers with different components for different purposes but no matter what computer you physically build the design will remain the same.
Invisible Good Design
Do you remember the diagram below from Chapter 2?
That diagram laid out the basics of how a computer operates. When we talk about architecture, we need to get into a bit more detail, and for this, we use the Von Neumann Architecture diagram.
Central Processing Unit (CPU)
The Central Processing Unit (CPU) is the logic circuitry that processes the instructions that are given to the computer. The CPU is seen as the main and most crucial integrated circuit (IC) chip in a computer, as it is responsible for interpreting most computer commands. The CPU performs most basic arithmetic, logic and I/O operations, as well as allocate commands for other chips and components running in a computer.
The terms processor is used interchangeably with CPU, although strictly speaking, the CPU is not the only processor in a computer. The Graphical Processing Unit (GPU) is the most notable example. Nevertheless, the term processor is generally understood to mean the CPU.
The basic elements of a processor include:
The Arithmetic Logic Unit (ALU), which carries out arithmetic and logic operations.
The Control Unit (CU), which is the unit that manages instructions.
Registers, which hold instructions and other data.
Cache, a fast memory that improves the efficiency of a CPU.
Some computers will operate using a multi-core processor — a chip containing more than one CPU. A CPU is typically a small device with pins on it facing down in a motherboard. CPUs can also be attached to a motherboard with a heat sink and a fan to dissipate heat.
Most processors today are multi-core, which means that the IC contains two or more processors. This results in the following advantages:
Enhanced performance.
Reduced power consumption.
More efficient simultaneous processing of multiple tasks.
Memory Unit
The Memory Unit consists of RAM and ROM, also referred to as primary memory or main memory. Unlike secondary memory, this memory is fast and also directly accessible by the CPU. The diagram we showed earlier also illustrates connections to secondary memory, for example a hard disk.
Random Access Memory (RAM) is volatile. That means data is retained in RAM if the computer is on, but it is lost when the computer is turned off. When the computer is rebooted, the OS and other files are reloaded into RAM. RAM typically comes in sticks, and is added to the motherboard through specially dedicated RAM slots.
RAM can be compared to a person's short-term memory and a hard disk drive to a person's long-term memory.
The I/O Subsystem
The input and output devices appear to the CPU as if they were memory devices i.e. input appears as if the CPU is reading from memory and output appears as if the CPU is writing in memory.
A port is a connection, found at the front or back of a computer, that permits a computer to connect to a peripheral input or output device.
Putting it all together on the motherboard
In desktop computers, the above components are located on the motherboard. Here is a sample of a typical motherboard so you can visualize these components.
Buses
If you're wondering how all these components communicate with each other, that's where buses come in. Buses are physical wires that move data around the computer and also send out control signals to synchronize internal operations. There are 3 types of buses:
Address Bus A unidirectional (one way) connection that carries signals related to addresses between the CPU and memory.
Data Bus A bidirectional (two way) connection that sends the data between CPU, memory and I/O subsystem.
Control Bus A bidirectional (two way) connection that sends signals to control and coordinate activities between components in the CPU.
The Graphics Processing Unit
You may have heard of this if you're interested in gaming. The Graphics Processing Unit (GPU) is a another processor on modern computers that is specialized in the creation of both 2D and 3D images. It lightens the weight of the CPU by doing some heavy graphics processing.
Here is what it looks like on a motherboard.
Let's talk speed
Speed varies a lot between different components of a computer. In a typical computer, the order from fastest to slowest component is as follows:
Construction of a Gaming PC
One of the best ways of understanding the core components of a computer is by watching one being built. This video shows the construction of a Gaming PC. Bear in mind that laptops work differently but the basic components are the same; they just usually come in different shapes and sizes to fit into smaller enclosures.
Comentarios