OpenMSX runs a bit too slow

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Por jvidal

Rookie (18)

imagem de jvidal

26-05-2021, 06:09

Hi!

This is a long-standing bug, I just never got around to reporting it...
The thing is that at 100% emulation speed, OpenMSX runs just a bit too slow. Setting the emulation speed to 110% makes it run closer to a real MSX speed. This is easily noticed on titles like "Hype" or "Pippols" or "zanac-EX".
Is there something I should check, besides just rasing the emulation speed to 110% or 120% ?

My machine is powerful enough to run openmsx at full speed (8xAMD FX-8320 @3,5Ghz & 16GB RAM, Geforce GT1030 2GB)
(If I set the emulation speed to, say, 150%, it runs way too fast, so obviously my machine can handle it)

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Por santiontanon

Paragon (1420)

imagem de santiontanon

26-05-2021, 06:28

Are you sure it's not because of the 50hz vs 60hz of some MSX machines? it could be that you are using a 50Hz machine in openMSX, and comparing it to a 60Hz physical MSX, which would match with that 120% you are mentioning.

Por NYYRIKKI

Enlighted (5776)

imagem de NYYRIKKI

26-05-2021, 06:36

I think the MSX model you are emulating is not exactly same as the model you are now comparing it to. Games tend to work 20% faster on Japanese models when compared to European MSX models.

Por AxelStone

Prophet (2965)

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26-05-2021, 08:27

santiontanon wrote:

Are you sure it's not because of the 50hz vs 60hz of some MSX machines? it could be that you are using a 50Hz machine in openMSX, and comparing it to a 60Hz physical MSX, which would match with that 120% you are mentioning.

My 2 cents for this. You are playing a 50hz machine but you are used to 60hz machine. Acording to your explanation (110% speed) is the most feasible explanation, NTSC computers are 16% faster than PAL computers.

Por jvidal

Rookie (18)

imagem de jvidal

26-05-2021, 20:34

I think my original MSX is a 60Hz machine, since I ive in south america. My MSX machines were manufactured by Telematica in Argentina (Talent DPC-300 and TPC-310), based on Daewoo original designs.
The machine I use mostly on OpenMSX is "Boosted MSX2 EN", but I'm not sure if it is a 50hz or 60hz machine.

Por jvidal

Rookie (18)

imagem de jvidal

26-05-2021, 20:37

On the othr hand, other emulators, like fMSX or blueMSX run at normal speed , without specifiying if it's 50 or 60hz...

Por ToriHino

Paladin (710)

imagem de ToriHino

26-05-2021, 21:05

"Boosted MSX2 EN" is indeed a 50Hz ('european') machine. You can check this by using PRINT VDP(10) in basic: 0 means 60hz and 2 means 50hz.

So as already mentioned above, that's indeed the reason why it is a bit 'slower'. I know at least BlueMSX for sure also shows a difference, at least when the correct setting for the frequency is selected. It has the option to set a configuration to 50, 60 or automatic (so it could be that the default setting happens end to be 60 or automatic).

Luckily with an emulator you can just pick any configuration, so it's easy to pick another one which is on 60hz (for example "Boosted MSX2+ JP").

Por santiontanon

Paragon (1420)

imagem de santiontanon

26-05-2021, 23:05

jvidal wrote:

On the othr hand, other emulators, like fMSX or blueMSX run at normal speed , without specifiying if it's 50 or 60hz...

That is a pure coincidence of which is the default machine that each emulator happens to have Smile

Por NYYRIKKI

Enlighted (5776)

imagem de NYYRIKKI

26-05-2021, 23:27

ToriHino wrote:

that's indeed the reason why it is a bit 'slower'

Indeed 'slower' and percentages are quite misleading ways to describe this problem... Computers displaying on 50Hz frame rate can actually execute 20% more code/frame... There are just 16.6% less frames. Smile In real life only thing that changes is the screen update frequency, but in MSX game and music progress was typically tied very tightly to screen update speed unlike in modern computers.

There is also no "best default" as it depends a lot where you are coming from. Most of popular emulators originate today from Europe that was using mostly 50Hz TVs. On the other hand most of the best games and MSX standard it self originate from Japan that was using 60Hz TVs.

Let me try to open the problem a bit more: Typically when you run program designed for 60Hz on 50Hz it just runs 16.6% too slow. When you run program designed for 50Hz on 60Hz, it either runs 20% too fast or it starts to skip screen updates and in worst case drops to 60% of original speed due to lack of CPU time. Some games (on MSX2 and up) tend to force the screen update to some fixed selection regardless of the selected machine... or in best case the game may even compensate the music & stuff depending of screen update speed (typically a bit more modern games). In some games the 50Hz/60Hz selection does not really matter as the limiting FPS factor is the MSX CPU and not the screen draw. (maybe most typically 3D games and BASIC games) and some games / game loaders has a hot key, command line option or settings screen to select between 50Hz/60Hz (ie. disk cracks, ROM-loaders and such) On MSX1 the 50Hz/60Hz is fixed on hardware and the screen update speed can not be changed by software.

Por JohnHassink

Ambassador (5576)

imagem de JohnHassink

27-05-2021, 01:54

So yeah, maybe we should be a bit more careful before calling something a "bug", when we just don't comprehend something? Smile
The openMSX team is quite serious about their stuff.
Anyway, Case Closed.

Por jvidal

Rookie (18)

imagem de jvidal

27-05-2021, 02:28

thanks, you guys!

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