VOGONS


First post, by Aro2220

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In a lot of games, like prince of persia, there is a Cpu Cycles and Frameskip at the top.

However, in some games like Quarantine or Magic Carpet, these 'cpu cycles' disappear. All I can do is increase frameskipping...which doesn't slow down the speed of the game...it just skips frames.

I really want to enjoy these old classics. Can anyone tell me why I can't control CPU cycles on some games and if there is a good way around it?

Reply 1 of 5, by DosFreak

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There are real mode games and protected mode games.

REAL mode games were roughly introduced before 1993. (Prince of Persia is a REAL mode game)
Protected mode games were roughly introduced after 1993+. (Quarantine and Magic Carpet are protected mode games)

When you run a REAL mode game in DOSBox then DOSBox only uses 3000 cycles and you must increase cycles manually. This is because if DOSBox used auto cycles for these games then they wouldn't work properly in most cases.

When you run a protected mode game in DOSBox then DOSBox uses a variable amount of cycles up to a certain percentage. If you want to control this then you need to used the "fixed" switch with the "cycles=" option in DOSBox.conf. Refer to the DOSBox manual for usage.

Last edited by DosFreak on 2010-06-13, 05:45. Edited 2 times in total.

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Reply 2 of 5, by robertmo

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with the latest dosbox this thread wouldn't even appear.

by the way what dosfreak said is already explained more properly in the manual

Reply 3 of 5, by wd

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It would, if the answers would contain timer-based game specifics but we're not there yet.

Reply 4 of 5, by Aro2220

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I had no idea about the real/protected mode stuff. I still don't really understand what they are but I can look it up now since I have key words.

I had version 0.73 so I updated to 0.74 but I think this would have worked in either.

I needed to edit the config file (it now has an easy dosbox options link on the start menu which just opens the config file with notepad)...to find a line called cycles=auto and change it to cycles=fixed 14000

and that works great. The best part is that I am left in control of the cycles and that lets me get the game working with just the right amount of lag.

Thank you everyone.