How to emulate 68060/50 expansion board fast-ram?

Nut · 09 February 2010, 16:15

Which settings do I need to get fast-ram emulated?

I'm trying to use 040/060, JIT/no-JIT, Z3 fast 128MB, adjustable between CPU and chipset. With these fast-ram throughput seems to be exactly the same as chip-ram throughput, about 2MB/s. The only setting that seems to affect this is "fastest possible, but maintain chipset timing", but it could be that the emulation "as whole" just runs many times faster.

I'm sure my code resides in fast-ram and is writing to fast-ram, since AsmOne tells me all this. If I put my code in chip-ram and write to chip-ram, the bandwidth is exactly the same judging from my colorbars!?

From the thread below I read that 060/50 fast-ram could do 35-50MB/s.

http://eab.abime.net/showthread.php?p=625007

If indeed 060/50 Amigas can get 35MB/s+ throughput I might code something nice for the AGA platform. I have no previous coding experience on anything "AGA".

Thanks for any info.

Toni Wilen · 09 February 2010, 16:56

Your timing routine is getting confused for some reason. Both Chip and Fast RAM are extremely fast in JIT modes (no DMA contention emulated)

Nut · 09 February 2010, 18:03

Sorry! My mistake! I got 2MB per frame and not 2MB per second

That would add up to 100MB/sec in the "adjustable between cpu and chipset" mode. I got 1500MB/sec in "fastest possible" mode.

Funny thing is that chip-ram access is as fast as fast-ram access in the emulation, 100MB/sec, but in real life would be a lot slower, somewhere in 2-8MB range I believe. So I guess I just have to rely on bandwidth calculations while I'm coding and target to some ranges below "a real Amiga".

Another thing is how I'm going to figure out how fast my code runs on a real 060/50 machine, when I only have 030/50 to test, and WinUAE does not have cycle exact 060 emulation? I'm speaking to myself now... I'll figure out something.

Toni Wilen · 09 February 2010, 20:22

JIT is always as fast as possible (direct memory access, bypasses everything, it does not even know addressed memory type)

68000 (and unexpended 68020 since 2.0): accuracy first.
68020+ = performance first.

Emulating 68040/060 caches and pipelines and fpu and.. will be complex and practically impossible to get it right. Also it would need extreme host CPU power..

09 February 2010, 16:15	#1
Nut Registered User Join Date: Feb 2010 Location: Helsinki, Finland Posts: 36	How to emulate 68060/50 expansion board fast-ram? Which settings do I need to get fast-ram emulated? I'm trying to use 040/060, JIT/no-JIT, Z3 fast 128MB, adjustable between CPU and chipset. With these fast-ram throughput seems to be exactly the same as chip-ram throughput, about 2MB/s. The only setting that seems to affect this is "fastest possible, but maintain chipset timing", but it could be that the emulation "as whole" just runs many times faster. I'm sure my code resides in fast-ram and is writing to fast-ram, since AsmOne tells me all this. If I put my code in chip-ram and write to chip-ram, the bandwidth is exactly the same judging from my colorbars!? From the thread below I read that 060/50 fast-ram could do 35-50MB/s. http://eab.abime.net/showthread.php?p=625007 If indeed 060/50 Amigas can get 35MB/s+ throughput I might code something nice for the AGA platform. I have no previous coding experience on anything "AGA". Thanks for any info.

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09 February 2010, 16:56	#2
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,540	Your timing routine is getting confused for some reason. Both Chip and Fast RAM are extremely fast in JIT modes (no DMA contention emulated)

09 February 2010, 18:03	#3
Nut Registered User Join Date: Feb 2010 Location: Helsinki, Finland Posts: 36	Sorry! My mistake! I got 2MB per frame and not 2MB per second That would add up to 100MB/sec in the "adjustable between cpu and chipset" mode. I got 1500MB/sec in "fastest possible" mode. Funny thing is that chip-ram access is as fast as fast-ram access in the emulation, 100MB/sec, but in real life would be a lot slower, somewhere in 2-8MB range I believe. So I guess I just have to rely on bandwidth calculations while I'm coding and target to some ranges below "a real Amiga". Another thing is how I'm going to figure out how fast my code runs on a real 060/50 machine, when I only have 030/50 to test, and WinUAE does not have cycle exact 060 emulation? I'm speaking to myself now... I'll figure out something.

09 February 2010, 20:22	#4
Toni Wilen WinUAE developer Join Date: Aug 2001 Location: Hämeenlinna/Finland Age: 49 Posts: 26,540	JIT is always as fast as possible (direct memory access, bypasses everything, it does not even know addressed memory type) 68000 (and unexpended 68020 since 2.0): accuracy first. 68020+ = performance first. Emulating 68040/060 caches and pipelines and fpu and.. will be complex and practically impossible to get it right. Also it would need extreme host CPU power..

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