Wikipedia says: A demo (demonstration) is a non-interactive multimedia presentation made within the computer subculture known as the demoscene. Demogroups create demos to demonstrate their abilities in programming, music, drawing, and 3D modeling.
The key difference between a classical animation and a demo is that the display of a demo is computed in real time, making computing power considerations the biggest challenge. Demos are mostly composed of 3D animations mixed with 2D effects and full screen effects.
That is a good definition. A demo is something artistic and technical that you simply watch. The same way you watch a painting or listen to music. The main advantage of using computer is that all arts (drawing, music, programming) can be mixed to create something beautiful. Usually demos program also a have high technical level.
Any computer or hardware device can be utilized to generate art. There truly are no limits. Today, you can find demonstrations on pharmacy signs, buildings, watches, or even microwaves! The only boundary is your imagination.
Here are websites that are references in demoscene:
This blog will mainly be centered around the Amiga computer from the Commodore company. The picture above is one of my A500 (in 2012). I've bought two A500 this year (because I did not had one before this. My A500 had died around 1990).
The Amiga is a nice 16 bits computer that had a great success when it was released.
Edit 2024:
In 2012 I bought the 2 Amigas for around 40€ each. Today the price of all Amiga stuff has risen a lot. It's hard to find an A500 in France below 150€. In general, all retrocomputing and retrogaming items have increased in value. Surely because we are older and ready to put more money into these old items. So prices are rising. That's the (sad) law of the market.
I still have my Amiga 1200 from 1990 and my 5 1/4 floppy drives (quite rare). Since, I've bought Amiga hardware here and here. Here the list of Amiga stuff I've got today:
Some machines are not running and need repair. That's also a fun part.
To give the state of the art of computers and gaming at that time, here are some arcade great games. When I was on holiday in Italy I could play some. Arcade was the top of what gaming proposed at that time. Not yet at home, but soon will be.
Built like a movie, that game play video sequence depending on player actions. Extremly punitive.
Wireframe game with speech samples.
From Nintendo. Screen resolution is 256x244.
Timeline of Arcade games history
Intro Step2