Authentic A4000 speed

[Mixon]

Hi!

What is a good WinUAE setting for the authentic speed of the A4000?

With this configuration (68040+MMU+FPU, cycle exact, 8X multiplier {28.3 MHZ} ) the SysInfo speed test results in only half of the A4000 (68040 25 MHZ) reference speed.

I see that, with this settings, for some reason (on the CPU tab) the „Cycle Exact CPU Emulation Speed” setting not works, any value will result in 13,3 MHZ CPU freq in the showconfig programs (like WhichAmiga).

Thank you:

Mike

[Waccoon]

It's pretty difficult to get accurate performance for the higher-end CPUs using fast RAM. Cycle-exact emulation only really applies to chip RAM.

From what I understand, when WinUAE is running code out of fast RAM, it assumes the CPU can use every available cycle. On real hardware, not all cycles could be used because either the RAM chips or the memory controllers couldn't run fast enough to keep up. This is a big reason why modern memory boards using FPGAs and/or SRAM chips run a lot faster than vintage DRAM boards.

For this reason, among others, the speed of the emulation will vary a great deal depending on the machine and memory configuration, regardless of the CPU. When I set up WinUAE with the same configuration as my real A1200, chip RAM performance is spot-on, but fast RAM runs about 40% faster than the real thing. Actually, WinUAE does a surprisingly good job of emulating the '020 cache. The speed of floating address spaces is completely wrong, though (and it doesn't really matter).

[Mixon]

I see, with disable cycle exact, and +85% CPU speed results 25MHZ and same performance in the SysInfo.

This right or not?

[Waccoon]

Sounds about right, but bear in mind that CPU performance will vary depending on what operations the machine is doing and what RAM is being used. SysInfo just runs a single benchmark, while AIBB runs a variety of different tests. There really isn't a way to make the CPU perform exactly like real hardware under all conditions.

You can do cycle-exact emulation with chip RAM since the behavior of the Amiga's custom chips and glue logic is very well understood, and there's no major RAM timing differences between OCS/ECS/AGA. Fast RAM performance varies a lot depending on what memory board you're using, and what bus bridge is used.

[Mixon]

And what is the best setting for the games right speed?

[Mclane]

Sysinfo isn't the greatest benchmarking tool when it comes to the faster emulated machines. As said, the way to get A4000 accurate speed is to get a real A4000. System specs and settings on the PC really play a part in this..

[AC/DC HACKER!]

A bit after I started with WinUAE I got my A4000 disks copied to HDFs and..then I focused on the same question. Tip: You won't get the same speeds. A little slower, sure, a LOT faster, indeed. Using CPU/Emulation Speed/Approximate is closest you're going to come to what the zero40 and zero60 do,,but it's a little slower.

Personally, set it to Fast as Possible, disable JIT and enjoy. Unless you notice some problems with WHDLoad games, or ...whatever program, then go back to Approx. speed and troubleshoot then. I love the faster, when using DOpus 5 for LZX, LHA, DMS, and more. The 2 may be swapped on-the-fly but do Not swap JIT on the fly. Genetic Species runs fantastic with JIT on using 640x480...just a clue there. HA!

UAE makes the Amiga optionally speeeeedy as we would have wanted it to become. But also allows for much slower when needed. If I want actual speed, I power on my A4000+CybertormPPC/zero60. Which, honestly, isn't being used as much as UAE.

I wish I knew how to program PPC code, I'd write a new qemu-uae.dll. Anyway, pardon some slight OT.

[Marce]

Originally Posted by Mixon

Hi!

What is a good WinUAE setting for the authentic speed of the A4000?

With this configuration (68040+MMU+FPU, cycle exact, 8X multiplier {28.3 MHZ} ) the SysInfo speed test results in only half of the A4000 (68040 25 MHZ) reference speed.

I see that, with this settings, for some reason (on the CPU tab) the „Cycle Exact CPU Emulation Speed” setting not works, any value will result in 13,3 MHZ CPU freq in the showconfig programs (like WhichAmiga).

Thank you:

Mike

please note the 040/25mhz in sysinfo gets 19.5 mips
the 040/40mhz gets 30 mips

so if you want the authentic 040 speed
in winuae set fastest possible cpu
then adjust the slider which is below ...ie -50% or -40% until you get desired mips on sysinfo

[stobros]

Originally Posted by Marce

please note the 040/25mhz in sysinfo gets 19.5 mips
the 040/40mhz gets 30 mips

so if you want the authentic 040 speed
in winuae set fastest possible cpu
then adjust the slider which is below ...ie -50% or -40% until you get desired mips on sysinfo

This one helped me a lot. Thanks.