Fundamental Computer Abstractions.

It is all abstractions built on top of each other.

Gestalt Abstraction
Image source: http://web.siat.ac.cn/

First, there was electricity.

And then switch devices were built to receive electric signals and make them exist in two states: on or off

Now, we know a switch device can only represent two states on or off (binary)

More states can be represented by combining multiple switch devices:

- 2 Switch devices together can represent 4 states
- 3 Switch devices together can represent 8 states
and so on...

In summary, n switch devices can represent 2ⁿ states.

Then the single information was termed to be a bit.

A 1 bit machine – can store two pieces of information

A 2 bit machine – can store 4 pieces of information

and so on…

And then the naming system for bits was created:

4 bits – 1 nibble

8 bits – 1 byte


Early computers were 8 bit computers, this meant they could process 8 bits (1 byte) at once.

Total possible states with 8 bits/1 byte is  2⁸ = 256

The next abstraction was to make meaning of these binary format for human interaction and ASCII (American standard code for information interchange) was born, ASCII mapped alphabets, numbers, special and control characters to the last 7 bits of the byte. The first mapping being 00000000 – NULL and the last value being 01111111 was mapped to – DELETE control character.

Characters – cslib
Image source: https://cslib.co.uk/

More and More Abstractions…

One of many other important abstractions created was the OSI model or IP model that enabled computers communicate easily with each other, this eventually gave birth to what we call the INTERNET today.

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