A long time ago, I used to be a demomaker...
The beginning
I fell in love with computers at an early age, I was about 6 or 7 I believe and already the computer science club in my small town near Nancy caught my interest. It was 1982 and there were only early Thomson computers and Commodore Pet's. That was AWESOME ! 
I dreamt about great computer hackers I could see in movies like Tron, WarGames or even Short Circuit. Now I realize they were total crap but I still watch them with emotion as I remember these days 
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At the age of 9, my parents finally managed to gather enough money to buy me a computer for Christmas, it was a Matra Alice 90. I believe it's something that existed only in France, as many other computers at that time : small companies could build entire brands that only a hundred of people would buy worldwide. Some brands had more success than others like Amstrad, Apple, Atari, Commodore, Sinclair but many were forgotten. Anyway, the Alice 90 was sold in a nice big red plastic suitcase so you could take it anywhere. The package design was (I realized later, to my great surprise) made by the famous artist Jean Giraud a.k.a. Moëbius.
You would't believe it if I told you that computer had a cassette recorder to load and save programs for which you had to set the volume level to the exact right value or else, the data would get completely scrambled and the loading/saving would fail ! Yes ! You actually had to spend about 10 minutes tweaking the recording/playing level of the cassette recorder to manage to load a program ! It was a real cassette recorder, the guys at Matra didn't even bother to build a special purpose recorder and just used a normal one painted red so it matches the central unit. 
So I started to learn Basic (as written on the box ) which was hardcoded in ROM and my first program ever (discarding the obvious "Hello World !") was already something graphical : I made a frame by frame animation of a dog walking on a scrolling sidewalk, getting by a lamppost, stopping, raising its back leg and... well... pissing on the lamppost. Come on ! Cut me some slack here ! I was only 9 ! Huhu.
Anyway, I still remember the notebook with the little squares I drew to make the dog sprite. Now I would probably ask an artist to model the dog, and I would either ask an animator to rig and animate the dog mesh or I would code a procedural dog animation so I don't bother to animate the thing myself ! 
Evolving
I think I kept programming the Alice until I was 12 but I was also closely monitoring what other computers could do and I was drooling on the ever growing amount of colors of the Amstrad 6128 (16 colors among 26 guys!), its fine pixel graphics and... it had a floppy disk drive ! File:S13.jpg (although the 3" disks were not normalized and awfully expensive)
I sold my Alice 90 to a friend and bought an Amstrad. Basic was also in ROM so it was quite easy to continue my Alice trips, except I had so many more colors and RAM and speed. Can you imagine ? 128Kb of RAM and a 4MHz processor ! Wooohooo !
There, with the Amstrad I started to copy a bunch of alphanumeric codes that were listed in some magazines and at the end, if you hadn't made any mistake, that would make a program ! I didn't quite understand that was assembly code and it appeared like some kind of magic. But I started to realize there was quite a difference between my small and slow Basic programs and these programs that displayed sharper graphics at a much higher speed... Something was very wrong !
The early demo days : the Atari ST
When I was 13, I went to a trip to Paris with my parents and met the new Atari 520 ST for the first time in a FNAC franchise. My jaws litterally dropped to the ground. That was IT ! I had to get one but it was sooo expensive !
I finally managed to convince my parents 1 year later and if you had ever needed the perfect symbol picture for happiness, that would be me coming back home with my brand new ST !
Basic was no longer integrated to the machine. You had to get a software to start programming : that was the famous GFA Basic ! It's the first time I ever came across the concept of "compiling some code". I could see that compiled GFA Basic code would run slightly faster compared to interpreted code but I didn't understand the reason until many years later when I started to code in C on the PC.
So I continued Basic coding in GFA for some time. I was 14 at the time and just saw the trigonometric Sin & Cos functions so I started to write a program that would rotate a cube in 3D. I actually came close to finding the actual rotation formulas by trial and error but at some angles the vertices would strangely collapse on themselves. It's only months later I came across the actual formulas explained with nice graphics.
During that time, a good friend of mine living in the neighborhood fed me with disks he got from a friend of his who got them from a friend and so on... We were swapping cracked disks and I didn't understand yet the concept of cracking but I was happy to be able to write some code, play some games and discover new stuff from these cracked stuff... That's also the first time ever I saw demos. Actually, that were only crack intros at the beginning of a games compilation. Namely, the first one ever I guess was from a cracking crew called "The Replicants" (certainly from Blade Runner I suppose but I didn't know the reference at the time). That was it ! I was hooked ! I wanted to do what these guys did ! Raster bars in nasty eye-molesting RGB colors ! Scroll texts ! Sprite animations ! Even early wireframe 3D ! Sometimes even in fullscreen !!! How the hell did these guys manage to kick out the screen borders ???!!