![]() ![]() well, if it would have been in real time. Taking all of this into account, then it's obvious that the juggler is less of a great example of what can be done in HAM mode on an Amiga, but rather a splendid exercise to overcome the built-in limitations. Thus the only advantage of HAM is a possible higher colour usage (within the defined limits).īottom line: HAM is a nice idea, if the output is destined for a TV-like device and displaying more or less TV like, static pictures. In terms of memory bandwidth a plain (no additional tasks) 320x200 is always the same, no matter if 64 colour mode or HAM is used. It just leaves the CPU running (almost) unharmed. So using less bandwidth doesn't exactly help to display a picture. Increased resolution and colour depth can slow down the CPU from the nominal 7 MHz to an almost full stop. Each access to generate video does slow down the CPU. Chip RAM - the area where graphics reside - is shared between chipset and CPU. Next, the assumed 'bandwidth efficiency' is less of a general advantage but rather a way to overcome limitations of the Amiga hardware. Since HAM's memory representation is also tied to the plane structure of all Amiga graphics, each pixel manipulation (may) take six separate write operations. Effectively reducing the horizontal colour resolution to a third - 106x200.ĭue to this dependence between successive pixels manipulating HAM for animation is rather complex and needs quite some CPU to avoid unintended effects - if they can be adverted at all. So if a colour is needed that is not one of the 16 base colours, up to two intermediate pixels with somewhat similar colours are needed (*2). Every other pixels colour is generated by modifying one (RGB) channel's 4 bit value. Only the 16 colours of the basic palette can be used at any given position (*1). ![]() Well, to start with, while HAM mode could display 12 bit colour (4096) on screen, these weren't independent of each other. The Amiga advantage for Juggler was both the size of the colour palette and the bandwidth efficiency of HAM This is only indirect an answer, but rather targeted at what it seams are misconceptions about Amiga (RAM) bandwidth and inner workings of its HAM (Hold and Modify) graphics mode. How long was it before another roughly $1,000 computer was available with the palette, resolution, and graphics bandwidth to faithfully recreate Juggler? So, I'd say approximately $1,000 is a suitable metric for an inexpensive system that might match the Amiga. These were not only much more expensive than Amigas, but they were normally limited to 256 on-screen colors and did not have an architecture supportive of full-screen 30 fps animation.Īn Amiga 1000 cost $1,495 with 512K in 1986 and an Amiga 500 with 512K was $699 ('87). I know that by the late 1980's, there were Macintosh II and PC w/ SVGA computers available. Nearly full-screen animation, since a relatively large portion of the scene must be modified between each frame.Īny port that was attempted would need to target a machine with the above attributes, at minimum, in order to faithfully recreate the Juggler demo.Sufficient graphics memory/bandwidth to play at a smooth 30 fps.A high color-depth framebuffer capable of 4,096 simultaneous colors at 320x200.But the actual playback of the animation was an impressive use of Amiga graphics unmatched in other low-cost computers of the time. ![]() While Juggler was a tech demo of both raytracing and animation of the resulting frames, I'm not concerned with the rendering process simply because any computer with enough RAM could do it given sufficient time. Unlike the earlier Boing! demo, which barely tapped the Amiga's graphics abilities and was widely aped on other computers, Juggler does not seem to have ever been ported. The demo was created by Eric Graham (who went on to develop Sculpt3D) using raytracing to both render the scene and play the animation on a stock 512K Amiga 1000. The Amiga Juggler was the 2nd very popular demo to appear for the Amiga Computer early in its lifespan. ![]()
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