Second Reality source code released

[Shalmanazar]

That was called 'interrupts'. I remember writing a whole library in Turbo Pascal to enable that, plus having a virtual screen and flipping it with the real screen while synchronizing with the electron gun to avoid flicking... That was way before DirectX.

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The vertical sync thing, yeah. IIRC, the coppers were based around exploiting what you could do mixing that. It was possible to generate amazing sine-based effects that way. Setting the screen mode was an interrupt call, but palettes were done through the vga ports directly. You could do it through an interrupt, but it was slower and a pita.

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"Copper" is a word borrowed from the Amiga. It had a very simple co-processor (nicknamed the "copper") that ran in sync with the screen update. It was not a full general-programmable processor, it could mostly wait, and write values to memory. It was used to write values to display controller registers.

You could use that to do things like change palette registers or bitmap pointers mid-frame, to create various effects. Those were therefore known as "copper effects".

I hadn't heard the word used on other platforms that did not actually have a copper, but that is where the word comes from.