VOGONS


First post, by bluejeans

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I'm trying to run dos doom (it's a long story why, want to see how old mods run on older hardware) and the highest emulated cpu I can get running at 100% if about a 486dx25, on an i7-870 (stock 2.93ghz). On my i5 4690k at 4.2ghz overclocked cpu's all the way up to a pentium 200mmx run flawlessly at 100% emulation speed. Is there really such a huge performance difference with my two systems or should I be looking into something else causing the problem?

Reply 2 of 12, by bluejeans

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SA1988 wrote:

It really depends on the host due to the current dynarec, I mean, if you want a perfect 100% speed in the Pentium MMX at 200Mhz, you need that 4.2GHz machine.

Changing that setting to 1 makes it run flawlessly. If I overclock my i7-870 to 3.9ghz should I expect to be able to run, say, a pentium 75 (since that's about 30% faster than a 486-100)

Reply 3 of 12, by Jo22

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bluejeans wrote:

I'm trying to run dos doom (it's a long story why, want to see how old mods run on older hardware) and the highest emulated cpu I can get running at 100% if about a 486dx25, on an i7-870 (stock 2.93ghz).

Um, that's odd. Became single-core performance of current x86 generations that poor ? 😕
I ran an emulation of a 486DX50 in PCem on an AMD K9 dual-core (~12 years old system) at full speed (no dynarec).
In 2016, I've taken a screenshot of it running an NES emulation on Win 3.1 :
Re: A problem when trying to install a Living books game on Windows 3.1 on PCem.

bluejeans wrote:

On my i5 4690k at 4.2ghz overclocked cpu's all the way up to a pentium 200mmx run flawlessly at 100% emulation speed.
Is there really such a huge performance difference with my two systems or should I be looking into something else causing the problem?

Do you need MMX support ? I'm asking, because the Pentium MMX is more complex than a 486.
On real hardware, a nifty design might be beneficial for performance.
But in emulation, that's not always the case. In an Emulation, a simple design with a high cycle rate might be better.
If you like, try to play with the dynamic recomplier switch.

Edit: Several fixes.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 4 of 12, by bluejeans

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Jo22 wrote:
Um, that's odd. Became single-core performance of current x86 generations that poor ? :?: I ran an emulation of a 486DX50 in […]
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bluejeans wrote:

I'm trying to run dos doom (it's a long story why, want to see how old mods run on older hardware) and the highest emulated cpu I can get running at 100% if about a 486dx25, on an i7-870 (stock 2.93ghz).

Um, that's odd. Became single-core performance of current x86 generations that poor ? 😕
I ran an emulation of a 486DX50 in PCem on an AMD K9 dual-core (~12 years old system) at full speed (no dynarec).
In 2016, I've taken a screenshot of it running an NES emulation on Win 3.1 :
Re: A problem when trying to install a Living books game on Windows 3.1 on PCem.

bluejeans wrote:

On my i5 4690k at 4.2ghz overclocked cpu's all the way up to a pentium 200mmx run flawlessly at 100% emulation speed.
Is there really such a huge performance difference with my two systems or should I be looking into something else causing the problem?

Do you need MMX support ? I'm asking, because the Pentium MMX is more complex than a 486.
On real hardware, a nifty design might be beneficial for performance.
But in emulation, that's not always the case. In an Emulation, a simple design with a high cycle rate might be better.
If you like, try to play with the dynamic recomplier switch.

I can exceed a pentium 90 with dynamic recompiler - why was it turned off to start with?

Reply 5 of 12, by Jo22

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bluejeans wrote:

I can exceed a pentium 90 with dynamic recompiler - why was it turned off to start with?

To be honest, I'm not 100% certain. But I think it has to do with compatibility/stability.
Same reason why DOSBox has an auto core setting, I guess.

In an older PCem I tested, the dynarec did not work flawlessly with *some* 486 settings.
The emulated machine did POST, but it freezed or hang at the HDD detection/the boot process.
Entering CMOS SETUP did work fine, though.

Another thing I noticed with the dynarec was jerky performance in DOS sometimes.
Similar to running DOS in Virtual PC 200x with IVT/AMD enabled.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 6 of 12, by bluejeans

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Jo22 wrote:
To be honest, I'm not 100% certain. But I think it has to do with compatibility/stability. Same reason why DOSBox has an auto co […]
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bluejeans wrote:

I can exceed a pentium 90 with dynamic recompiler - why was it turned off to start with?

To be honest, I'm not 100% certain. But I think it has to do with compatibility/stability.
Same reason why DOSBox has an auto core setting, I guess.

In an older PCem I tested, the dynarec did not work flawlessly with *some* 486 settings.
The emulated machine did POST, but it freezed or hang at the HDD detection/the boot process.
Entering CMOS SETUP did work fine, though.

Another thing I noticed with the dynarec was jerky performance in DOS sometimes.
Similar to running DOS in Virtual PC 200x with IVT/AMD enabled.

How can I enable it in pcem, there's no line for it in its' .cfg file?

Reply 7 of 12, by Jo22

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bluejeans wrote:

How can I enable it in pcem, there's no line for it in its' .cfg file?

In the menu bar, you can choose Settings->Configure to find a checkbox right below the emulated CPU type (486).
The line in the config file is "cpu_use_dynarec = 1".

86Box should have a similar setting (haven't used that since quite a while).

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 8 of 12, by bluejeans

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Jo22 wrote:
In the menu bar, you can choose Settings->Configure to find a checkbox right below the emulated CPU type (486). The line in the […]
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bluejeans wrote:

How can I enable it in pcem, there's no line for it in its' .cfg file?

In the menu bar, you can choose Settings->Configure to find a checkbox right below the emulated CPU type (486).
The line in the config file is "cpu_use_dynarec = 1".

86Box should have a similar setting (haven't used that since quite a while).

What should I be able to emulate with a q6600? I'm guessing the emulator only uses a single thread? Single-threaded performance is about 30% less than my 870.

Reply 9 of 12, by eton975

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bluejeans wrote:
Jo22 wrote:
In the menu bar, you can choose Settings->Configure to find a checkbox right below the emulated CPU type (486). The line in the […]
Show full quote
bluejeans wrote:

How can I enable it in pcem, there's no line for it in its' .cfg file?

In the menu bar, you can choose Settings->Configure to find a checkbox right below the emulated CPU type (486).
The line in the config file is "cpu_use_dynarec = 1".

86Box should have a similar setting (haven't used that since quite a while).

What should I be able to emulate with a q6600? I'm guessing the emulator only uses a single thread? Single-threaded performance is about 30% less than my 870.

With my Q6600 PC @ stock (2.4Ghz), I'm just about able to do a decked out 486DX2-66 rig without NukedOPL (it uses tons of CPU time). A Pentium-75 runs at full speed in some games but only at ~75% in others, a K5-75 hovers between ~80-100%.

Overclocking, if your board supports it, should help, as will overclocked/fast RAM. (DDR2-800/1066, DDR3 1066/1333)

Reply 10 of 12, by valnar

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Sorry to piggy back here, but I also noticed that when I start up a Win98 machine in the latest PCEM, the audio is smooth. When I do the same with 86Box it sounds a bit choppy. It doesn't matter what CPU I pick. It's almost like the default buffering options are different between the two emulators.

Anyone else experience that? I like the features of 86Box more than PCEM, but PCEM seems a bit more polished.

Reply 11 of 12, by SA1988

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valnar wrote:

Sorry to piggy back here, but I also noticed that when I start up a Win98 machine in the latest PCEM, the audio is smooth. When I do the same with 86Box it sounds a bit choppy. It doesn't matter what CPU I pick. It's almost like the default buffering options are different between the two emulators.

Anyone else experience that? I like the features of 86Box more than PCEM, but PCEM seems a bit more polished.

Probably because of the renderer, PCem has wx-sdl2, but 86Box still has DDraw and Direct3D, in any case, you can use the Epox machine which doesn't have choppiness.