Dosbox always maintains 60 Hz or 70 Hz depending on the video mode set by the emulated program, unless demand is too high for the host CPU. In other words, Dosbox is already locked to a particular framerate. With fixed cycles, as long as the host CPU can keep up, the program should run the same way as on a real computer (with a throughput comparable to the Dosbox cycles setting).

I don't think you can affect the "real-time" speed of Dosbox except with the unlock speed button or by starving your computer's CPU resources.

> a game will speed up during less graphics-intensive sections

all old and modern games behave like that on a real computer 😀

just take any first person shooter and stand with face close to the wall and check how fast you can rotate, than turn your face to an opened area with a lot of architecture/enemies and see how slow frame rate you have 😀

If a game has no frame limit nothing you can do. But if a game has a frame limit you can help the performance by having a very powerful computer so that it will never slow down cause it can handle everything and it won't speed up cause of the frame limit of the game.

Some games allow you turn on/off frame limit for example Grand Theft Auto 1.

I have noticed that gulikoza's build has got fps counter. Would it be possible to make a simmilar feature like cycles=max that would be not cpu usage dependant but fps dependant? So that no game will run too fast in dosbox.

It still won't be perfect as if the screen is not updated fps will be 0 and game's time will still be too fast.

robertmo wrote:

> a game will speed up during less graphics-intensive sections

all old and modern games behave like that on a real computer 😀

When I say "speed up", I mean that quite literally. Older games (at least when played via DOSBox) seem to be quite sensitive to framerate fluctuations. Take the game Quarantine, for instance; I assume the game was originally meant to be played at around 25 FPS, because if the framerate exceeds 25, everything looks very "unnatural" - the characters run around like they're in a Buster Keaton movie, the vehicle is almost impossible to control at higher speeds, etc... but if it drops below, it becomes a slideshow.

Video memory slowdown might help

Another candidate for "game speed fluctuation" is Magic Carpet. If i set the cycles too high in vga mode, people zoom around very quickly, and the game is impossible to play. In SVGA mode and fixed cycles play is at normal speed in some scenes, a bit too fast or a bit too slow in others, even though the host CPU usage is nowhere near the maximum. I think this is not only because of DOSBox, but because of the game engine, too. Maybe it's a combination of the two factors. A FPS based "autocycle" setting could be interesting for some games, but i can't say if this could be implemented. I think if it's possible to measure and display the number of FPS's, it should also be possible to increase or decrease cycles accordingly. Maybe something like a "targetfps_xx" setting?