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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?
insanityprawnboy wrote: ↑Wed Jan 25, 2023 3:53 pmI 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?
insanityprawnboy wrote: ↑Wed Jan 25, 2023 3:53 pmI 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 
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.
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.
Give the CPU speed a bump it works for some games. It will probably make the beeper sounds a bit funny though.