The CPU (Central Processing Unit) is the brain of a computer,” is a catchline most of us have been familiarised with since secondary school. After branching out into non-tech fields of work, the specifications and features of a PC/laptop may appear to be incoherent due to forgotten lessons and will require some re-brushing.
Although electronic computers have been around since World War II, ENIAC, the ability to put the CPU in a single circuit board and chip, became a reality only in the 70s, when the Intel 4004 became the very first commercially available microprocessor. These tiny chips are responsible for executing instructions, performing complex calculations, and enabling seamless functions on computers and smartphones.
A processor’s architecture consists of several key components; Inside the CPU is a silicon rectangle comprising millions of transistorised circuits that carry electronic signals into and out of the chip, a Control Unit (CU) which receives the inputs, decodes instructions fetched from the memory and sends signals to perform arithmetic or logical operations, and an Arithmetic Logic Unit (ALU) which performs arithmetic or logical operations using registers, apart from other components.
Processors are designed to follow a specific set of instructions, often represented in the form of machine code. Machine code or machine language is composed of binary values, which are interpreted by the processor. When a user gives an input through an external device, it is directly sent to the CU, which fetches the instructions from the main memory and decodes it into machine language to determine the operations to be performed.
The ALU carries out the operation specified by the instructions and sends it back to the CU, which provides the output to the user. In a CPU, these three phases of operation loop continuously and are regulated by a clock. A CPU clock rate is measured by the number of electrical pulses per second, or Hertz. With each pulse of the CPU clock, a cycle of fetch, decode, and execute operations is done. Modern CPUs can touch clock rates approaching 5GHz, which means they operate at 5 billion clock cycles per second. These operations are performed inside the Core. Cores are units within the CPU that can execute instructions independently or together to complete tasks.
Therefore, the more cores you have, the faster your computer will be. Nowadays, there are multiple-core processors; Dual, Quad, Hexa, Octa, Deca, etc. Some processors also employ a technology called Multithreading. A thread is a virtual version of a CPU core that breaks up physical cores into virtual cores or threads to increase performance. The Integrated Circuit (IC) is located on a motherboard through which it communicates with the memory, hard drive, display, and other external devices.
While Intel 4004 had about 3,500 transistors in its IC, today, a processor like Intel Core i9-13900K has about 25.9 billion transistors. The denser the logic circuits of a CPU, the more the number of cores, the higher the number of instructions it can perform per clock cycle. A fast CPU isn’t everything. A processor, no matter how powerful, may not be able to easi ly render the latest applications. That’s where other components like the graphics card and memory come into play. When all components synchronise, the electronic wizard does its magic.