Show HN: I recreated 90s Mode X demoscene effects in JavaScript and Canvas
45 comments
·June 17, 2025TuringNYC
Great nostalgia! You should also do the multi-colored rolling pipes, that was a staple!
luismedel
Nice. But if I remember correctly, Mode X was a special VGA mode to squeeze a bit more performance (due to planes and full graphics memory addressing), not the "normal" MCGA 320x200x256 (13h)
If you're interested, I also implemented a few effects like lens[0] and Jare's fire[1] along with some other amusements[2]
[0] https://toys.luismedel.com/lens/index.html
gneissguise
Thanks for sharing the link! I remember the lense demos, and I remember downloading one or two of them from a BBS that had NSFW pictures rendered in the background.
wvh
That's one way to stimulate memory...
I was so into this in the mid-90s. I tried some assembly but I wish I would have been better at the maths part back then.
pentaphobe
Neat! The nostalgia is palpable.
Off topic: we always referred to mode-x variants as MCGA, TIL that's more of a colloquial term than a technically accurate one [1]
[1]: https://en.m.wikipedia.org/wiki/Multi-Color_Graphics_Array
gneissguise
Thanks for sharing, I do not believe that I was familiar with that term at the time.
stuaxo
Would like to see an old school vowel landscape.
dr_dshiv
Thanks for putting this together!
I’ve been thinking a lot about demoscene in a Vibecoding era. Demoscene was often very close to the metal; Vibecoding is often completely abstracted from it.
To explore this tension, I’m cohosting an 8bit game design workshop (pico8) in Amsterdam this summer. Just for fun.
Working with intense constraints can bring a lot of creativity. I really want to see how AI affects the workshop vibe.
elpocko
>very close to the metal
>(pico8)
But PICO-8 with its integrated tools and Lua programming is super high level, pretty far removed from "8bit". It's only 8 bit in aesthetics, entirely artificial and forced. Why not write games for the 2600, the C64 or the NES to experience real constraints of an actual 8 bit platform, the actual "metal."
dr_dshiv
I know, tell me about it, we’ve been debating this, tbh. We landed on pico8 to introduce the ideas of creativity within constraints as there is a very active community and nice tooling. We’ve done NES workshops before, but always with CS students and eproms. 6502 assembly isn’t that complicated, but can be scary.
elpocko
I've been thinking about making a fantasy computer/console that uses an emulated 65C02 CPU, maybe a bit simplified -- every instruction only taking 1 cycle, for example. You could use all existing tools for the 6502, like the amazing 64tass, and there's an interesting high level language called prog8 (https://github.com/irmen/prog8) that's relatively easy to use. Not sure if there's any interest for something like that.
ceronman
Hi! That sounds very interesting, where can I find information about this workshop? I am interested in participating.
imiric
Vibecoding is entirely antithetical to demos.
Demos aren't just pretty visuals. Their entire purpose is to showcase the skills of the programmer in accomplishing something remarkable within a constrained environment, or within artificially imposed constraints. Using exorbitant amounts of resources to run a machine learning model to generate a muddy mixture of existing demos goes completely against this spirit. The idea of the two together is, frankly, repulsive.
dr_dshiv
Be repulsed then! We are doing the workshop specifically to explore this tension. I’m well aware that times are weird.
This workshop is actually a forerunner to a workshop on demos with quantum computers, where the constraints are very real and creative participation is very lacking.
gneissguise
It was my pleasure to work on and share, glad you liked it!
kookamamie
Nice. Except that Mode X was not usually called 13h. The former would be 320x240 and the latter 320x200. Technically X would be a variant of the 13h, though.
ale42
And actually, INT 13h is the BIOS interrupt to access block-based disk I/O functions (like sector read, track format, etc.). The INT used for mode-setting is 10h (with AH=00h and AL=13h as mode for 320x200 at 256 colors).
gneissguise
Thank you both for the corrections, I was a teen in the 90s so I could have had it wrong or misremembered.
I just looked up the 13h interrupt and you are absolutely right!
gneissguise
If anyone is interested in doing algorithmic art while learning Clojure/ClojureScript then I highly recommend checking out the Quil library:
https://landofquil.clojureverse.org/
Just lean into the declarative lisp style and immutable data and make some beautiful art to share with others!
juhanakristian
Well done! These look very authentic. I remember creating the fire and plasma effects when I was first learning how to code in the late 90s.
gneissguise
Oh yes, I have similar memories mixing asm and pascal together in Turbo Pascal to get interesting results!!
TrackerFF
The vector one is still alive and kicking. I've lost count how many current websites have that one on their landing page.
gneissguise
Yep it has totally made a resurgence with the background animation trend showing up in modern web UI.. except without the pixelated appearance and the green phosphor color.
p1dda
Thanks! So great to watch these demos in 80-90's of the wizards creating these spectacular visuals.
gneissguise
Heck yeah you're welcome! It was a blast to put together
rollulus
Good job. Looks authentic. But you forgot the rotozoom!
gneissguise
D'oh! Now that I'm in my mid 40s there's so much I've forgotten!
Thank you for the reminder
stuaxo
Wonderful. Did you simulate through weird bitplains of VGA?
I found them hard to get my head round, still do.
gneissguise
Excellent question. This is more a modern chunky pixel framebuffer, not planar.
The spirit of the project, however, was to emulate the tricks that bitplanes made famous. The plasma and flag effects, for example, don't move any pixels; they just cycle the color palette's offset against a static pattern, which is a direct software simulation of that classic Amiga hardware hack.
After 25 years of writing software, I was feeling nostalgic for the kinds of things that got me into programming in the first place: the old DOS demoscene. I spent a weekend seeing if I could recapture some of that INT 13H VGA magic using today's web tech, but with the old-school constraints of doing it from scratch.
The result is this portfolio of ten classic effects running in a single HTML file. It's all vanilla JavaScript writing to a <canvas> element, with no external libraries. It was a fun challenge to implement things like:
* The color palette cycling and smooth fading in the Plasma demo. * The buffer-averaging algorithm for the Fire effect to make the flames feel more natural. * The distance-based texture crossfading in the Tunnel to create the illusion of flying through different sections. * A 2D scalar field for the Metaballs to calculate the surface normals for that classic blended, metallic look (I did the best I could with the given constraints).
It was a great exercise in getting back to first principles and a reminder of how much those early demo programmers could accomplish with so little. I hope it brings back some good memories for others who grew up with this stuff.
I'd love to hear about your favorite classic demos or if there are any other iconic effects you think would be a fun challenge to add.
Cheers!