12 September 2017, 16:28 | #201 |
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Sounds stupid. RTG should be super fast without or nearly no CPU usage. Maybe an RTG chip on board would do the trick. To have AGA a bit faster is nice/good but for compatibility and future I would go the RTG way.
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12 September 2017, 17:36 | #202 |
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Sounds wrong. The Vampire has something like 400 MB/s mem bandwidth. A 640x480x8 resolution at 60 Hz takes 17.5 MB/s away from the bandwidth available to the CPU. This is only about 5%. 16bit, 24bit and 32bit resolutions take 2, 3 and 4 times 17.5 MB/s away from the CPU, obviously. The CPU will often work inside its caches during such times. The SAGA's display DMA also has a buffer and will leave the memory interface to the CPU as long as the buffer is well filled which also reduces the impact of the display DMA on the CPU. Of course, if you run really HD resolutions in 32 bits, the display DMA has quite some effect on the CPU but this is no difference to any other "chipset graphics" computer on the market. My Intel Atom began to crawl in such a scenario. Obviously such high resolutions aren't viable for games on an Amiga anyway.
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12 September 2017, 17:58 | #203 |
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Does anyone know, what is the current status of Vampire SAGA? Is it possible to program directly like for OCS/ECS/AGA? Does it have similar DMA control registers for bitplane, sprite, blitter, copper, audio and disk, located at $dff000?. And copperlists etc. of course.
I hope the documentation will be better for SAGA than for AGA..currently I have only some VGA compatible displays around, and it was difficult enough to open correctly a 640x480 screen with AGA in hardware. There are some docs available for AGA, but they aren't quite right. I'm seeing things like people opening screens with -8 modulo in 4x fetchmode, instead of setting display DMA data fetch regs properly, or screens that are wrongly aligned/missing data. |
12 September 2017, 18:06 | #204 |
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All SAGA features are controlled through registers in the traditional register address space. This also means that they can be controlled by the copper. Of course, copper tricks won't be available through RTG libraries. So some hardware banging may even be necessary to unleash the full power of SAGA (e.g. planar overlays over chunky screens, totally free hardware scrolling of chunky screens etc). Otherwise SAGA would only be very fast AGA plus very fast RTG (which is pretty nice already).
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13 September 2017, 03:01 | #205 | |
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13 September 2017, 10:38 | #206 | |
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Apart from the fact that, as Grond points out, the RTG feature of the Vampire soaks up RAM bandwidth (more with higher resolutions), it is also unaccelerated. That means that the CPU will need to do the job of the blitter, further degrading the performance. And that's even discounting the fact that 060+RTG games are just so 2001. |
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13 September 2017, 11:17 | #207 | ||
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13 September 2017, 11:38 | #208 |
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Is it? Perhaps it has improved massively recently, but last time I saw a Vampire playing Payback it struggled to get anywhere near the speed of my A1200 with a Mediator + Voodoo 3 at the same resolution, and had nowhere near the resolution capabilities (said Voodoo-equipped A1200 tops out at 1920x1200x24@60Hz). Maybe you're comparing it to cards like the Picasso IV, which are even further obsolete than the Voodoo, or maybe you're comparing specific benchmarks that favour the Vampire; I can't tell since the link is blocked here. But some real-world comparisons would be nice.
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13 September 2017, 11:47 | #209 |
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It is a real-world comparison with a Cybervision 64 and P-IV setup. It is probably not quite up to Voodoo 3 speeds, but hopefully it can get close with further optimizations (resolution cannot though).
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13 September 2017, 13:11 | #210 | |
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While your mediator setup can drive high resolutions, the bus that connects the graphics memory to the processor is so slow that you can watch the pixels being updated one after the other. Not my definition of a fast graphics solution. |
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13 September 2017, 13:58 | #211 | ||
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At lower resolutions of course it's instant - 1600x1200 for example has no perceptible screen switching time. |
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13 September 2017, 14:10 | #212 |
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I think the point here was that perhaps Payback was designed specifically to take advantage of Voodoo 3 cards. The only way the Vampire could compete with that is to make it Voodoo 3 compatible (which seems like a silly way to go). You could also look at it another way that software that was designed to utilize AMMX and the other Vampire specific features does not run well on non-Vampire software (if at all). It is not the fault of the hardware or the software specifically, but a combination of the two.
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13 September 2017, 14:15 | #213 |
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Well, I was comparing the software rendering mode since I prefer that to the Warp3D mode. Obviously comparing two different executables optimised for different hardware would be pointless in this context. That game mode is graphics card independent, though I'm sure it relies heavily on standard P96 functions that are accelerated on most cards, just like Intuition and any other system-friendly software.
Pushing a screen to video memory pixel-by-pixel would obviously be extremely slow on such a setup, and much faster on a Vampire. Thankfully most software doesn't use such methods. |
13 September 2017, 14:22 | #214 | ||
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13 September 2017, 14:22 | #215 |
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Well, then I think this new P96 driver should provide significant speed boosts in Payback since the improvements looks like they are generally scattered all over the P96 accelerated functions.
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13 September 2017, 14:24 | #216 | ||
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13 September 2017, 14:36 | #217 | ||
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Ah, so it's no longer a simple framebuffer then? Yes, that should massively improve things alright, because on paper the Vampire should run rings around my A1200 setup. Clearing it of such bottlenecks as a simple framebuffer will make it a far more impressive piece of equipment. |
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13 September 2017, 14:48 | #218 |
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The original P96 driver didn't use AMMX at all. The new one uses AMMX2.
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13 September 2017, 14:52 | #219 |
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13 September 2017, 14:55 | #220 |
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Okay, that statement was probably wrong then.
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