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Old 21 November 2009, 21:32   #13
niobyte
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Join Date: May 2007
Location: Perth Western Australia
Posts: 147
Have you tried running the demo without JIT (Just In Time) emulation.

Also try using the 68060 CPU option with FPU -> CPU Internal -> More compatible ticked.

You will find with JIT emulation since it is cached and pre-compiled the demo runs way too fast compared to its native speed on a real 68060.

I have honestly tried myself without using JIT it has major issues trying to emulate this demo. I have found that using 68030, 68040 or 68060 with the above configuration of 'more compatible' it ends up with a guru just after the rain intro.

I have found with the 68020 + FPU it completes the whole demo but the timing is completely gone and the parts take a long time to appear but eventually do way too late.

The demo completes in around 8 mins with the 68020 + FPU config without JIT and set to 'fastest possible but maintain chipset timing'. Mainly due to seeing a blank screen a long time between parts. It also missed the girl with rose picture (with JIT turned on it seems to show this picture). When each segment is seen at an acceptable frame-rate faster than what it is natively seen on a 68060 @ 50 MHz.

I had tested this with the latest version of WinUAE. It seems older versions of WinUAE seem to be able to run this demo a little better for some reason (runs faster in older versions, mainly due to emulation in-accuracy). Although, not much differs in reality.

You will find with the 68060 config without using JIT if you view that you will see that it runs a similar speed to how it is on a real 68060, well it is on mine. This will depend on how fast your CPU is. With the 68060 option it does not go past the intro unfortunately.

For JIT settings:
8MB cache | Constant Jump | FPU Support | No Flags | InDirect

You will find under JIT at least completes properly, but is just a lot faster (depending on how fast your CPU is) compared to how it runs on a 68060 @ 50 MHz. I have run this demo on my A1200 BPPC @ 210MHz with 68060 @ 50 MHz. The speed of it is pretty close to the YouTube video.

I guess the only chance of seeing this demo at the correct speed and a lot of other 68060 demo's. Is if cycle-exact emulation is done for a 68060 equipped Amiga. At the moment WinUAE only does cycle-exact emulation for the Amiga 500.

The versions I tested this on were: 1.4.6.0 & 1.6.1.0

Quite interesting that you were able to get it to work at a more accurate speed in 1.5.0

You can ignore this post if you want

I am just posting my findings.
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