Emulate Amiga of any imaginable speed

[aros-sg]

Hi. Is there or wouldn't it be nice to have an option in UAE to configure host to emulated time ratio? Standard is 1:1 -> Amiga clock running in UAE ticks as fast as a clock runing on host OS. So that's realtime.

But if for example that would give roughly a 68060 at 500 Mhz on a specifc computer but one would like to emulate one at 5000Mhz then in theory that should be possible by simply modifying the UAE host timing code to lie, and for example say that only 1/10 second has passed when in reality it was 1 second. The UAE user will see a clock app in AOS run 10 times slower than it should but to the emulated Amiga and it's OS and it's apps it looks like it is really a 10 times faster machine.

Such a thing would for example help to check if certain benchmarks still calculate their benchmark results correctly even when the benchmark is executed much faster than expected by the benchmark tool because of running on hyperfast theortical hardware of 68060 at 10000 Mhz or whatever. And it can be done with JIT disabled.

[Seiya]

the only way to do it should be modifing "cpu_multiplier" in WinUAE CPU Panel, but you have set cpu speed approximate A500/A1200 and set cycle_exact=true.
i tried but there is no change in speed. i try with Gamebase and thanks to it's script i can set any speed.
i setup also A1200 with 68020 at 14 Ghz and the speed is like Jit, but without using it. Of course are not real clock but you see the jit speed but with maximum compatibility.
So you can run software at maximum speed, but without problem that usally you have with jit enabled.

[Leandro Jardim]

Originally Posted by aros-sg

Hi. Is there or wouldn't it be nice to have an option in UAE to configure host to emulated time ratio? Standard is 1:1 -> Amiga clock running in UAE ticks as fast as a clock runing on host OS. So that's realtime.

But if for example that would give roughly a 68060 at 500 Mhz on a specifc computer but one would like to emulate one at 5000Mhz then in theory that should be possible by simply modifying the UAE host timing code to lie, and for example say that only 1/10 second has passed when in reality it was 1 second. The UAE user will see a clock app in AOS run 10 times slower than it should but to the emulated Amiga and it's OS and it's apps it looks like it is really a 10 times faster machine.

Such a thing would for example help to check if certain benchmarks still calculate their benchmark results correctly even when the benchmark is executed much faster than expected by the benchmark tool because of running on hyperfast theortical hardware of 68060 at 10000 Mhz or whatever. And it can be done with JIT disabled.

Originally Posted by Seiya

the only way to do it should be modifing "cpu_multiplier" in WinUAE CPU Panel, but you have set cpu speed approximate A500/A1200 and set cycle_exact=true.
i tried but there is no change in speed. i try with Gamebase and thanks to it's script i can set any speed.
i setup also A1200 with 68020 at 14 Ghz and the speed is like Jit, but without using it. Of course are not real clock but you see the jit speed but with maximum compatibility.
So you can run software at maximum speed, but without problem that usally you have with jit enabled.

I think aros-sg is talking about another thing.

You Seya, is talking about speed control. Toni already said this is not realisticaly possible now without the Motorola opcode data sheet, that is confidential and Toni don't have access. And aros-sg, is talking I guess, about a sort of "time machine" for WinUAE.

A "time machine" in the sense that the emulated time can be made relative to the host time, as such it doesn't need to be the original timestamp, and this way all events that WinUAE use to emulate the bus data transfers between the CPU and the chipset could be made to run slower or faster. I like to think it's a bit like Einstein's theory of relativity, but for CPU emulators. (that's why I called it a "time machine")

WinUAE could interpolate the host time to a ratio that the user would choose, for which WinUAE will eventually register in every event as it always does. Every new ratio that the user choose would scale the emulated time, the timestamp of the events, the clock cycles for every instruction and subsequently propagate change to the clock speed also.

Toni could use that to find an approximation of the number of clock cycles necessary to perform a certain opcode, by making experiments trying to tune the time ratio, until he finds a number that will scale correctly the cycles per instruction of WinUAE to match a real CPU in clock speed, and then take note of that value to update the WinUAE source code.

That idea of aros-sg's will not make WinUAE fast like an 68060 at 5 GHz on a 2 GHz Intel notebook, but what I like to think and what I hope aros-sg was wanting to explain, is that it divide the perceived CPU speed in one that is logical and fake and other that is physical and real, to facilitate future experiments with the WinUAE codebase, for tuning the cycles per instruction of each 68020+ opcode that are not identical to the real CPUs yet.

Sorry if I am saying a stupidity! The only emulator I did ever write was a Chip-8 interpreter for Windows, that I did not even come to finish...

[Leandro Jardim]

Sorry for appending this almost blank reply, I only want to say I updated my post above with more information about my thinking I was trying to explain...

[Seiya]

boh, however if someone need to have super fake GHz speed (but with jit performance) there is some chance to do it.
I think that what want to do aros-sg is impossible if is like you have understand

[Toni Wilen]

Originally Posted by aros-sg

UAE host timing code to lie, and for example say that only 1/10 second has passed when in reality it was 1 second.

FPS adj. in Display panel sort of does this already. It can be used to change chipset timing relative to real world.

CPU speed won't still match 500MHz or whatever even if some test program returns it.