Table of Contents
CPU
We all know that a CPU is the most important part of a computer. It is often referred to as the brain of the computer.
CPUs are silicon chips etched with millions of Transistors. Modern CPUs have several cores, each core being an independent processor in itself. The CPU itself has two parts, the Control Unit (CU) and the ALU (Arithmetic and Logic Unit). The Control Unit orchestrates the functioning of the ALU using the computer memory to receive inputs and store results and give outputs.
The ALU does all the hard work of both arithmetic (addition/substraction/multiplication/division) and Logic (comparisons like greater than, less than, equal).
In short, the CPU works to execute the commands we give to the computer.
Brief History of the Personal Computer
Mainframe computers with ability to process data electronically were created in the forties. Over the next 30 years, many companies like Digital Equipment Corporation (DEC), Data General, Hewlett-Packard and Honeywell-Bull were supplying huge mainframes computers which occupied several rooms and costed millions of dollars.
The seventies saw the emergence of the Microprocessor which is hailed as the single most important event leading to the digital revolution.
A calculator manufacturing company called Micro Instrumentation and Telemetry Systems (MITS), in New Mexico, USA, which had almost gone bankrupt, started selling hobby kit containing a microprocessor and some components with a housing for enthusiasts to assemble a computer. This Kit was called Altiare880. It was a big success.
Seeing the success of Altair, more models like Apple I, PET, and TRS-80 sprang into the market. Bill Gates with his friend Paul Allen wrote a version of programming language BASIC for this machine.
It was during these early years, in 80s, that IBM which was the manufacturer and supplier of mainframe computers, wanted to develop a Personal Computer. Instead of manufacturing all components themselves, IBM chose to use Intel’s 8080 Microprocessor.
IBM however did not want to rely on just one company to supply the Microprocessor and wanted another supplier to ensure guaranteed supply. This was when Intel was compelled to license Advanced Micro Systems (AMD) to use their x86 architecture in manufacturing microprocessors. Intel and AMD signed a technology Exchange Agreement.
IBM PC was released in 1981 and became a resounding success. While Intel and AMD provided the Microprocessors for the IBM PC, Microsoft provided it the first operating system called IBM PC DOS.
IBM however, permitted Intel and Microsoft to sell their products to other companies as well. As a result, many companies like Columbia, Eagle, Compaq, started developing IBM Clones.
In 1984 Apple came out with the first Macintosh PC with a GUI. This was the first computer with a Mouse and a Graphic User interface (GUI).
In 1986 Microsoft released their first Windows 1.1 Operating System.
By the mid-90s IBM Compatible PCs with Windows Operating system dominated the PC market.
PC’s then started evolving with emerging technologies and faster processors and innovative software for every domain of human endeavor.
CISC vs RISC
CISC
We know that for a computer to work, it needs software and hardware. The software talks to the hardware using words that the hardware understands. This vocabulary has specific words like add, multiply, store, load, etc., These words are instructions all of which form an ‘Instruction Set’ which is technically called as ‘Instruction Set Architecture’. A Software program is written using this instruction set vocabulary.
The x86 instruction set was developed by Intel in 1978 and was used for their first 16-Bit processor 8086 which was an extension of Intel’s 8-Bit 8080 processor. When developed, the first instruction set had 81 Instructions. Intel then developed successors to the 8086 processor naming them 80186, 80286, 80386, 80486 family of processors all of which ended with 86, and therefore the term ‘x86’ was coined to name the instruction set.
At that time Intel held the patent for the x86 instruction set. AMD was initially licensed to produce x86 microprocessors. This was later discontinued and went through a labyrinth of legal twists. Today Intel and AMD have a technology Exchange Agreement wherein AMD can use Intel’s x86 Instruction Set and in exchange Intel can use the AMD’s x86_64 Instruction Set.
So in the market today we have two main manufacturers of computer CPUs those being Intel and AMD.
The x86 Architecture Set is a Complex Instruction Set Architecture, meaning, more than one command is required to be carried out by the Hardware based on one command.
RISC
In the 1980s, another form of architecture set was developed by Scientists Berkeley, Stanford and IBM. It was called the Reduced Instruction Set Architecture (RISC). In RISC, only one instruction was given to the hardware at a time and the same was completed in one clock cycle of the computer. CISC instructions would often take three or four cycles to complete.
In CISC an instruction like GET the VALUE in Register A, ADD 100 to it, STORE the result back Register B would be a single instruction in CISC. Whereas in RISK it would be broken down to three instructions
- GET the VALUE in Register A
- ADD 100 to it
- STORE the result back Register B
Though RISK had meant more than 50% instructions compared to CISC, they could be executed faster, about 4 times faster, and thereby proved advantageous.
Today, most of our IPad. IPhones, Android devices use RISC architecture. All ARM based processors are RISC examples being, Apples A Series, QUALCOMM Processors, Samsung’s Exynos processor.
RISC architecture based CPUs need more RAM compared to CISC based CPUs.
So, we have in the market today computers and devices using CPUs using either an Intel or an AMD Processor. Mobile phones, IPhone would be having an ARM based processor.
Conclusion
In summary, the CPU is at the heart of your laptop’s performance. Understanding how it works and what specs matter can help you make smarter choices, whether you’re buying a new device or simply looking to optimize the one you have. It’s not just about speed—it’s about finding the right balance for your needs.
