An oversabi mod decided to remove my topic from here. Not to FP but into obscurity. Well done. I have brought it back.



This topic was written because an ignoramus admitted he was ignorant to how processors function. So I have taken it upon myself to explain the basics of processors to the best of my knowledge.

My hope is that we all become enlightened.

In March 1971, Intel released a product that would revolutionize the world as we know it. They released the Intel 4004. A CPU that went on to bring computing into homes and signalled the start of the PC boom of the 80s. This CPU was fitted with 2300 transistors and could execute 46,250 to 92,500 instructions per second. This CPU is a 4-bit CPU. In comparison, the Core i9 has billions of transistors and can perform 80 billion instructions in a second.

In this part, we’re going to talk about binary as a machine language, transistors and their significance, data, instruction and some simple basic CPU terms. Lets begin.


In digital electronics, everything is represented in binary. Binary is a system of counting in twos (or two numbers) which are 1 and 0. So in binary, 1=01, 2=10, 3=11, 4=100, 5=101, 6=110, 7=111 etc. These two numbers (1 & 0) represents dual (2) states e.g. 1 (on) and 0 (off) or 1 (up) and 2 (down). At it’s most basic state, each 1 or 0 is called a BIT.

A transistor is a semi-conductor that can be used to switch on or switch off electrical signals in a circuit. A bit is transmitted as a voltage level. So if inside a CPU, a transistor allows 10V for example to flow past a junction, it is regarded as a 1, if it allows no current to pass, it is regarded as a 0. When these states (1 and 0) are combined, the CPU generates data.

When 8 states or bits are added together, you get a byte. That is 10011011 = 1byte. A byte can represent 256 states ranging from 0-256, -128 to 127, it can also represent alphabets, colours, pictures or sound. Older CPUs were built with 4bit, 8bit(1byte) or 16bit(2bytes). When multiple bytes are joined together, you get a word. You can have a 32bit word, 64 bit word or even a 128bit word. The native word size with which a CPU is built forms part of its architecture.

10011101010101011000101011010110=32bit word. A 32 bit word can represent 4,294,967,295 states of data.

Now lets go back to our Intel 4004. Intel 4004 was a 4bit CPU so this means that when data passes through it, it passes in 4bits. The same applies to 8bit, 16bit, 32bit and 64bit CPUs. The architecture for smartphones currently is the 64bit by ARM.

The most important bits of CPU data are instructions. Instructions are elemental operations such as math commands that a CPU executes. They are unique bits of data that guide CPU operations e.g add, move data, fetch data, subtract, go etc. These commands are used in writing code. The entire list of instruction that a CPU supports is called an instruction set.

Each instruction has a binary representation (machine language) and a human readable presentation (assembly language). In other words, a CPU can also be said to be an instruction processing machine. The instruction set that a CPU comes with makes up its programming. A CPU works in three phases (fetch – decode – execute) that means, it collects the data from the ROM (storage), runs it through its instruction set, executes the commands and outputs the data. The process by which a CPU does fetch – decode – execute is called a CLOCK CYCLE, and the speed by which it completes on clock cycle is called a CLOCK SPEED.

Hopefully we can look at ALU and Logic gates as well as RAM function in the next topic.

Pic 1. An Intel 4004 4bit CPU showing how data passes through it.

Pic 2. An instruction set with assembly language and it's binary language

Pic 3. CPU and RAM

An 8bit CPU processes data in 8bits. That means data passes through in the form of 11001010. Remember that 8bit is equal to 1byte. 8 bit machines were more powerful than the bit ones and many of the best video games of the era ran on 8bit CPUs

The Mod go hid thread, e go tire.

Continue here: https://www.nairaland.com/5901141/introduction-cpu-basics-crash-course