DEV Community: Mariam Antar

A brief history of computers as we know them today

Mariam Antar — Fri, 04 Sep 2020 13:45:35 +0000

We've come a long way since the Apple 2 computer that birthed a new generation of personal computers. I often find myself thinking about the history of what came to be the tiniest personal computer we carry with us today, our mobile phones.

Where it all started

Thousands of years ago stones were used to perform simple calculations, the word calculate derives from the Latin 'calculus', which means small stone. Eventually people came to a realisation that this method of counting was inefficient as their tasks grew more tedious and required a lot of stones to perform larger calculations.

A more coherent and well organised system was needed. This was when the abacus came along, a wooden tool that allowed people to perform complex computations and counting. The date of when this 'computer' was introduced or who invented it is unknown and heavily debated. You might have seen an abacus in a toy store before, they are still being used today.

One step forward: The invention of the mechanical calculator

In the 17th century the mechanical calculator was invented by Blaise Pascal who was a French mathematician, physicist, inventor and writer. Although a well known pessimist, one of the greatest minds in the areas of science and mathematics. A child prodigy from an early age, Pascal had worked out the first 32 propositions of Euclid by the age of 12. He then went on to invent the mathematics of probability and made significant contributions to the field. You may have heard of pascals triangle before.

The syringe we use today was amongst his many inventions. By the age of nineteen Pascal began inventing calculating machines and over 13 years built 20 machines. This included the first mechanical calculator which he created to help his father who was a tax collector. It was not only very expensive but very useless and became more of a status symbol for the wealthy.

The programming language 'Pascal' was named in his honour.

Gottfried Leibniz

Considered to be one of the most important logicians of his time Gottfried Wilhelm von Leibniz, created his own calculating machine called the Step Reckoner in 1673 that was inspired and built on top of Pascal's work and was able to use all four arithmetic operations (addition, subtraction, division and multiplication).

He was also the first to refine the concept of binary arithmetic and was an advocate of binary or base 2 system which is at the heart of digital computing.

Punch Cards

Looms were used to weave yarn into fabric and to create very complex patterns on carpet and cloth, a lot of manual labor was involved.

In the 1800's a weaver by the name of Joseph Marie Jacquard invented a programmable loom called the Jacquard loom that used punch cards to control every thread going back and front to the loom individually allowing him to create complex and repetitive patterns. His invention allowed patterns to be woven without needing a weaver. Soon enough his invention was acquired by the french government and he would earn a royalty on every loom sold. Weavers who feared unemployment attempted to destroy Jacquard's looms.

This machine using punch cards would go on to play a huge role in the development of computers as it was later adapted for computer data input.

Charles Babbage and his difference engine
Known as the father of the modern computer Charles Babbage was a polymath and gifted mathematician, inventor and mechanical engineer who built what was called a difference engine. But he stopped working on it to pursue another invention that he had built on top of the difference engine known as the Analytical Engine.

Babbage used punch cards in his Analytical engine inspired by Jacquard's use of punch cards to perform calculations automatically instead of entering them by hand manually. Although it is worth mentioning that his idea's never came to reality due to a lack of funding.

Ada Lovelace: The worlds first programmer

It took another mathematician and pioneer in early computing named Ada Lovelace to realise that the machine could be used for more than just calculations and developed the first algorithm for the engine. An algorithm is a series of steps to solve specific problems. She and Charles Babbage had been working on the analytical engine together. She became the first female programmer in the 1800's and is known to be the first programmer because she came up with the algorithm.

It was through Lovelace's discovery of algorithms programmed into the Analytical engine that it became the very first general purpose computing machine in history.

Herman Hollierth: The Census Tabulator

Herman Hollierth , an American inventor invented the first punched card electromechanical census tabulator inspired by the work of Babbage, this machine built for punch cards could read data up to 65 at a time and tally up the results. His machine was so successful that he went on to found the company Hollerith Tabulating Company which eventually became IBM.

Alan Turing and the Universal machine

You may or may have not seen the movie 'The Imitation Game' to know about one of the greatest minds in the history of computer science, Alan Turing. Alan Turing was highly educated having attended the University of Cambridge to study mathematics and after graduating he was elected to a fellowship at King's College.

In 1936 Turing proposed the concept of a universal machine which was later named the Turing machine. The concept of the modern computer today is largely based off of Turing's ideas.

Konrad Zuse: Inventor of the modern day computer

Konrad Zuse invented the world's first programmable computer in 1936 . It was the first computer to use boolean logic and binary to make decisions through the use of relays. Zuse later used punch cards to store data in memory.

In 1942 Zuse released the world first commercial digital computer known as the Z4.He is considered today as the inventor of the world's first modern computer.

Howard Aiken and The Mark I

Inspired by Babbage's analytical engine, Dr. Howard Aiken in collaboration with IBM began working on the Harvard Mark I calculating machine. It composed of nearly 1 million parts. Oneday the Mark I was not reading its paper tape input correctly and one of the first programmers of the Mark 1 discovered a computer bug, a dead moth blocking one of the reading holes of the machine. Her name was Grace Hopper and she was a pioneer in computer programming. Hopper is also credited with coining the word "debugging".

The Beginning of Modern computing: Vacuum tubes
John Atanasoff and a graduate student Clifford E. Berry invented ABC (Atanasoff-Berry Computer) that was the first electronic digital computer.It was a purely digital computer that used vacuum tubes and used binary math and boolean logic to solve up to 29 equations at a time.

The Colossus, World war 2 and Alan Turing and the Enigma Code
In 1943 the colossus was built in collaboration with Alan Turing to break german crypto codes.

When the war broke out, governments began pouring money and resources into computing research. They wanted to develop technologies that would give them advantages over other countries. As a result many advancements were made in fields like cryptography.

During the war, computers were used to process secret messages from enemies. A team of elite mathematicians, including mathematician Alan Turing and Gordan Welchman were tasked with cracking enigma after coming to a realisation that the german messages were unbreakable with traditional codebreaking techniques.There were millions of possible combinations. Turing built a machine with the help of his fellow mathematicians which eventually cracked the codes.

The movie 'The Imitation Game' was released in 2014 highlighting Alan Turing's life and the role he played in cracking enigma.

ENIAC: The first high speed electronic digital computer
In 1946 consisting of 18,000 vacuum tubes, the ENIAC was the first successful high speed electronic computer. It took concepts from atanoffs ABC and elaborated on them on a larger scale.

The Transistor and the TRADIC

In 1947 the first silicon transistor was invented at Bell labs and by 1954 the first transistorised digital computer was invented known as the TRADIC composed of 800 transistors.

In this era many contributions were made to the hardware and software aspect of computing.

The First programming language
Assembly was the first programming language to be introduced in 1949 , it was a way to communicate with the machine in pseudo language instead of machine language known as binary. But the first widely used programming language was fotran invented by John backus in IBM in 1954. Assembly is a low level language whilst fotran is a high level language.

Grace Hopper: Inventor of the First Complier
Compiling code was a very expensive and time consuming process but this all changed with an inventor by the name of Grace Hopper invented a compiler to remove the process of manually converted the programming code back into machine code (binary).

She also assisted with the programming language Cobol.

Integrated circuit: A hardware revolution

Whilst transistors were an improvement over vacuum tubes, they still had to be individually soldered together , the more complex computers became the complex connections between transistors became.

In 1958 this all changed with Jack Kilby of Texas instruments and his invention of the integrated circuit. It was a way to pack many transistors on a single chip, instead of individually wiring transistors. Integrated circuits sparked a hardwire revolution and helped the development of many other electronic devices such as the mouse invented by Douglas EngelBart in 1964 he also demonstrated the first GUI.

Xerox Alto

The first computer designed to support an operating system based on a graphical user interface (GUI) was the Xerox Alto. It would go on to influence the design of personal computers, the macintosh computer to be specific.

Steve Jobs and the Personal Computer

A pioneer of the personal computer known as one of the greatest inventions of the 20th Century, Steve Jobs founded Apple Inc along with Ronald Wayne and Steve Wozniak in 1976. They all worked at Atari. At that time computers were the size of a room and they had a vision of making computers small enough for people to use at home or in the office.

The Apple 1 was created in 1976 and only sold as a circuit board. Ronald Wayne left the company 12 days after the founding of Apple and sold his shared to Jobs and Wozniak for $800. In 1977 the Apple 2 was released and was greatly improved with a proper keyboard along with floppy disk drives.

Apple then went to XEROX PARC and used their GUI for future products. The Apple 3 and Lisa were released shortly after which both failed. It took the release of the macintosh in 1984 that changed the way people saw computers forever. The response to the release was a standing ovation.

Fast forward a few years later the iphone was introduced in 2007 and kicked off the smartphone market.

Computers as we know them today

We've come a long way from one of the most revolutionary inventions; the computer to the birth of the personal computer that has changed the way we do everything today from the way we communicate together via email, chat , video and social media on the internet to the way we function in our daily lives with applications that have allowed us to order food or catch a ride within minutes. We've come to rely on technology and it will continue to dominate various sectors for generations to come.

The OSI Model explained

Mariam Antar — Sun, 26 Jul 2020 08:23:26 +0000

The Open Systems Interconnection (OSI) is a framework and logical model that has outlined how applications and network systems communicate to each-other by breaking down the different components of network communications into layers. It was developed by the ISO (International Standards Organisation) in 1984.

The OSI model consists of seven layers that allow engineers to identify what is happening within a networking system and helps them to identify or solve a networking problem by looking at each individual layer. It is good to note that the OSI model is more of a theoretical model and not every layer is put into use like the TCP/IP Model which is more of a practical model used by engineers and only consists of four layers. The fifth and sixth layer are blended into the application layer and the data link layer is blended with the with the physical layer.

The OSI model is typically described from the top layer down, so what the end user is interacting with all the way down and is defined as follows:

7. Application - The top layer of the OSI model that is the interface that the user is interacting with the information on like browsers (Eg: Firefox, Brave), outlook for email, virtual terminal etc.

6. Presentation - This layer ensures that the data being sent from the application layer of the client is translated to a format the can be understood by the application layer of the server. When a user is interacting with the Application layer, that sends information down to the presentation layer where the data is formatted, converted, encrypted and decrypted. Data conversion, encryption and compression are the main functions on this layer. For example, If a user wants to upload a video to youtube they must use a certain format like mp4.

5. Session - This layer deals with communication, creating a session between the two computers. When you visit a website your computer creates a session with the server that you're trying to access to get data from and when you exit the website that session is terminated. You can think of this from the perspective of calling a friend. When that friend answers your phone call a session is established between both parties and when your friend ends the phone call that session is terminated.

4. Transport - This layer accepts data from the session layer and splits up the data into smaller segments which contain additional header information such as the destination port number, source port number and a sequence number.

Once created, these segments are sent to the network layer and the transport layer must ensure the bits delivered are the same as the bits sent without loss or duplication. If the transport layer detects a corrupted segment it will try to re-send the damaged data or restart the process from the beginning because the transport layer can also keep track of segments and retransmit those that fail. If no receipt of a segment is present it will time out the connection and throw an error.

This layer is the reason why more than one applications can use the same internet at the same time. When you are communicating with a website this layer decides how much information you will communicate to the website and how much will be communicated back.

3. Network - This layer is the layer that routers operate at, your ip address is at this layer. It looks at the content of the segments sent from the transport layer and adds more header information such as senders ip address and receivers ip address thus data packets are created on this layer. It is all about ip addresses and routing.

2. Data link - The purpose of this layer is to abstract the need for other layers to care about the physical layer and what hardware is being used, switches operate on this layer. When the data packets arrive at this layer more header information such as the MAC address is added to each packet and ethernet frames are created, thus at this level data packets are known as ethernet frames. A MAC address is the physical address for your network interface card or NIC and the NIC is responsible for reading or destroying frames on the receiver side.

- Quick breakdown on the structure of the ethernet frame

The ethernet frame on the data link layer has 7 main parts and it is a structured collection of information presented in a specific order. There are different types of frames, we will focus on the ethernet frame. The preamble tells the receiving NIC that a frame is coming. The last byte of the preamble is the SFD (start frame delimiter) which indicates the beginning of the ethernet frame. The SFD is followed by the MAC address of the recipient, and following that is the source MAC address which is the address where the frame originated from. The ether-type field is next and it describes the protocol of the contents of the frame. Next up is the payload which is the actual data from the high layers being transported. Finally we have the FCS (frame check sequence) which is used for error checking and the integrity verification of a frame.

1. Physical - The final layer is all the physical stuff that connects the computers together like wire, cables, panels etc. It is concerned with transmitted raw bits of data over a communication channel. Protocols at this layer accept frames from the data link layer and generates bits.It sends ones and zeros through network cables, a process known as modulation which allows devices on either end to understand that an electrical charge is either a one or a zero depending on whether copper or fibre optic wires are used. The data travels to the receiver completing a whole cycle of 7 layers.

The protocols on each layer:

Application:
The protocols that the user is dealing with at this level include HTTP, SMTP, POP3, IMAP4, TLS/SSL.

Presentation: Formats data to be viewed by the user. JPEG, GIF, TIF, PNG, MIDI, ASCII, ANSI, SSL, TLS etc.

Session: Establishes and terminates connections between two parties. NetBIOS, PPTP etc.

Transport: Responsible from the transport protocol and error handling, the protocol data unit at this level is called a segment. TCP, UDP, SCTP etc.

Network: Reads the IP address from the packet, the protocol data unit at this level is called a packet. Router, IP, IPSec etc.

Data Link: Reads the MAC address from the data packet, the protocol data unit at this level is called a frame Ethernet, Switches, WIFI, PPP, SLIP,Token Ring, ARCnet

Physical: Coax, Fibre, Wireless, Hubs