Recently i learned that the Amiga was effectively two computers in one. you had the 68k doing its thing, and then you had the custom chips doing their thing, and in the middle you had a shared RAM pool.
I guess to a degree the current CPU+GPU setup comes close, but that on the Amiga the GPU had priority.
That said, the tight coupling of CPU, RAM and the custom chips was perhaps the Amiga's Achilles heel. While on the PC you could switch out the various parts, the Amiga, at least on the A500, A600 and A1200, could not.
It's comparable with current CPU+GPU but on a vastly simpler scale. The copper only had 3 instructions! Blitter, well most things, were DMA controlled but the whole chispet had a ton of special registers that both CPU and copper could get at. You could set what got priority. Coders had to learn to wait on blits as anything else - OS as you moved a window, another app or screen could have got it first. Hence why many games just hit the hardware - keep it simple, and single threaded, and to hell with the OS. :)
About chip memory. Amigas had two types of memory Chip RAM and Fast RAM. Chip could be accessed by CPU and any of the chips, Fast RAM just the processor for programs and data. Modern CPU+GPU has two separate pools of RAM linked via the PCIe. If there were a similar architecture to the Amiga, but with modern complex silicon and design, I'm sure games coders would have dreamed up a few extra effects and tricks. Or maybe it wouldn't matter any more with the vast speeds we now reach, I don't know.
Incidentally that tight linking, display coprocessing, along with the DMA channels, and readily available genlock, is why it ended up a niche success in broadcast. Nothing else apart from £10,000+ dedicated things like a Quantel Paintbox (who bizarrely still exist) could touch it, especially after the Video Toaster came along.
The chipset needn't have been the achilles heel if Commodore had not been run by an asset stripping moron at the time. Designs were being done for follow on sets, but never made it, and we got AGA (a fraction of AAA) years late. I think they started on AAA in 87, and cancelled it or put it on hold probably a dozen times. The 3000+ was an astonishing prototype machine that only existed on Dave Haynie's desk, for ages. Commodore gave us the lousy cost cutting 4000 with IDE not SCSI as follow up.
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And still does. It's crazy.
It was years where you had to make the trade off of color depth and related display quirkiness at the expense of speed and performance
In the original demo they were showing the normal desktop screen, showing window dragging, resizing, showing text editors, clocks, shell and what not. Running 640x480 4 colour. The whole time you could hear the bang bang of the boing ball bouncing, but see nothing.
At some point a viewer asks "what the heck's that noise?" and the demoer pulls down the desktop screen to smoothly, and without glitching, reveal a 320x240 32 colour screen running the Boing demo behind it. In its day, that was almost unbelievable. PCs had just got 16 colour EGA and switching res resulted in a couple of seconds of monitor blanking or losing sync as it switched.
I can't remember if they also had a 4096 colour HAM image (Hold and Modify - a way of cheating with palettes and getting a LOT more colours) behind that.
The Amiga had virtual screens that operated a little differently to a modern approach - they could be massive with a monitor sized viewport onto it. They could have multiple resolutions and bit depths. They could be brought forward and sent back, and dragged (only up and down) to reveal multiple screens at a time. Visualise having a full size browser window, and dragging the whole window down to reveal the desktop, but switching resolution and colours as you go.
People left speechless.
The copper (display co-processor) allowed switching of palette and resolution, with 0 cpu use, on a particular scan line every frame.
It seriously took 10 years or more before a Windows desktop could move stuff around the screen as smoothly, mainly as the Amiga didn't actually move a lot of stuff a PC did. PCs were upping colour depth as they aged rather than chasing more speed though. Virtual screens were a shadow of their Amiga implementation.