128 Spectrum Running Slow?

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insanityprawnboy
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128 Spectrum Running Slow?

Unread post by insanityprawnboy »

I noticed when playing Rainbow Islands that the music slows down when the screen gets busy. Is that normal for a 128k Spectrum? And if not, how do I adjust the settings so it's right?

jordi
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Re: 128 Spectrum Running Slow?

Unread post by jordi »

insanityprawnboy wrote: Wed Jan 25, 2023 3:53 pm

I noticed when playing Rainbow Islands that the music slows down when the screen gets busy. Is that normal for a 128k Spectrum? And if not, how do I adjust the settings so it's right?

I don't remember about this game.

Did it had AY music or beeper music?

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Chris23235
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Re: 128 Spectrum Running Slow?

Unread post by Chris23235 »

insanityprawnboy wrote: Wed Jan 25, 2023 3:53 pm

I noticed when playing Rainbow Islands that the music slows down when the screen gets busy. Is that normal for a 128k Spectrum? And if not, how do I adjust the settings so it's right?

Just tried it on a the Speccy itself. It is the same on the original hardware. Nothing can be done about that. It's not unusual for a Spectrum game to run slower with lots of enemies (sometimes even without lots of enemies) and the music usually runs slower then.
You can play the game with 7MHz, then it is to fast, but not unplayable fast ;)

gambleboyen
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Re: 128 Spectrum Running Slow?

Unread post by gambleboyen »

This is apparently because the music channels are integrated with the sound effect channels, so when you make rainbows and this has a delay because of graphic congestion in the CPU, the sound effects are also congested and thus the music slows down to accomodate the delayed sound effects.

In contrast, try some of the later levels on Outrun. There the graphical slowdown is immense, but the music runs asynchronous to the action on screen (sound effects on a separate channel I guess) so there is no music slowdown even if the rest of the game is incredibly sluggish.

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pgimeno
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Re: 128 Spectrum Running Slow?

Unread post by pgimeno »

Some games' AY players are synchronised with the game's frame generation (which can be slower than the TV frame rate); some others are interrupt-driven and hence they run at a constant speed. That's normal.

From the above posts, it appears that Rainbow Islands uses the former method, while OutRun uses the latter.

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Re: 128 Spectrum Running Slow?

Unread post by Stinky »

Give the CPU speed a bump it works for some games. It will probably make the beeper sounds a bit funny though.

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