Amiga rasterbars are cool -- Meet the Copper, the hardware that helps make them happen

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Rasterbars are a common special effect on early computer games and demos. The Commodore Amiga's take on rasterbars are special due to the Copper, a special processor that synchronizes its activity to your monitor's image rendering hardware.
Thanks to Tyrel (@[e-mail])!
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References
Documentation:
* Amiga Coprocessor Docs (amigadev.elowar.com/read/ADCD_...) - Commodore's official documentation on the Copper
Examples:
* Code examples on Hackerbun (code.hackerbun.dev/TheIndustr...) - The code I wrote for the example copperbars in the video, written in C
* Copperbars in Assembler (vikke.net/index.php?id=copperb...) - Another description and demo for building copperbars, this one in Assembler
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Credits
* "Funin and Sunin" by Kevin MacLeod
incompetech.com
CC-BY 3.0 (creativecommons.org/licenses/b...)

[@elblanco5]

Title had "amiga", "rasterbars", and "copper" in it. Instant subscribe and like.

[@TheRenHoek]

Best explanation of copper I've ever seen. You have a true skill at breaking down complex subjects into digestible bites. Kudos!

[@arthurdaly3497]

I used to program Amiga demos, and I never remember it being that complicated 🤣 It was just something along the lines of, coding when you reach this screen position, change the colour palette. Amazing video about how it worked behind the scenes though. Hard to believe the effort put into it

[@sacredbanana]

It's been a year. The world needs moar moar!!

[@NathanBowmanMusic]

These are amazing - you're putting in TONS of work into these, and it's totally worth it!

[@cripplingmaymaystm9889]

Love the style of these videos. Informative and visually entertaining.
Great character designs too. Not complex, but very effective.

[@WeijuWu]

I like the style of your videos, both entertaining and educational and easy to follow 👍

[@bronwaith]

Thank you so much for all your videos! So informative 💖

[@sdf39882]

I've been trying to remember how all this used to work. Been a few decades since I've touched this stuff, but the itch to do some of this stuff like on a Commander X16 has been growing. The hardware is different, but X16 has a few unique things going for it and I've been thinking about learning that system to see what I could do with its different hardware capabilities. So, thanks for the very well produced explanation! I'd actually forgotten about copper. LOL

[@sacredbanana]

These are incredible. You're the best!

[@ecernosoft3096]

The most kid friendly Amiga tutorial ever. Gosh I wish this was the 80s and what kids learned in school instead of those Crapple 2’s.

[@windrago]

best ever seen and wonderful animations too!

[@fuzzynine]

Seriesouly, this is amazing. Don't know jack about assebler programming on the Amiga. Or at all. But your videos are a bliss!

[@scottbaddr4025]

Fantastic! I spent hundreds of hours with copper and blitter ages ago. Good times 😊

[@timjroughton9931]

Nice job ;)

[@youuuuuuuuuuutube]

Finally understood what it was really doing.

[@OLIV3R_YT]

Thanks ❤

[@saf271828]

OK, just gotta know. Where did you find the rasterized version of the Topaz font?!

[@MatthewSuffidy]

Well that does make seamless color bands, but what is more amazing is when the screen changes mode like indexed 4 and ham in a copper line. I guess that means the graphic chip can reconfigure mid screen?

[@ArneChristianRosenfeldt]

Like on C64 it all is just registers. On graphic cards with dedicated VRAM you could lose memory contents. But Amiga could not even change any refresh frequency ( only the pixel clock ).

[@hectorobregon3915]

Antic 2.0

[@michaelraasch5496]

Good old Copper. Those were the days.

[@ArneChristianRosenfeldt]

In 1993 on brand new AtariJaguar hardware you had an object list and could set interrupts on a scanline and let the GPU modify a register, like the horizontal resolution change in Doom.

[@michaelraasch5496]

@@ArneChristianRosenfeldt I used to develop for the Jag. It was still not the same.

[@ArneChristianRosenfeldt]

@@michaelraasch5496 yeah probably because racing the beam loses a lot of power when you have true color anyway and do 3d.
And also because the Jag is like a factor of 10 too slow to do 3d while racing the beam. Similar to the Nintendo DS.

[@thewelder3538]

Sorry, this is not a good explanation of the copper. Firstly, the copper has very little to do with bitplanes, although you do define the bitplane pointers in the copperlist. In fact the copper isn't restricted by the settings of the display window at all. Again, you do define DIWSTRT/DIWSTOP/DDFSTRT/DDFSTOP in the copperlist, but the operations of the copper happen over the complete width of the raster, so that's why you'll often see colour in the background whilst say, a scrolltext might disappear before the colour ends. The copper is also not affected by the Modulo.
Also, there are special waits used to cross into the PAL area of the screen.

[@thewelder3538]

@@igakoga2481 That's so true, except when the loudmouth has done loads of demos, many of which can be found here on yt. So obviously the loudmouth has no idea what he's taking about and therefore can be safely ignored.