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Timbucus · 5th Oct 2021, 6:00 pm

This is a problem that affects all systems where the frame is tied to the display frequency - there are only a certain number of cycles available and less at 60Hz (as there are 10 more frames in the same second).

If you say swapped a UK Issue 2 ULA with the US ULA and then tried to run some games that pushed the envelope they could well crash as they will receive an interrupt before they finish processing the previous one depending on how they are coded - it sounds like bikers read the available frame time and decided what to sacrifice - the advantage of a modern system and awareness of the frame frequency issue. That is why VGA-0 is ideal as it is exactly 50 frames a second.

There is a similar effect where often the US experienced the games and sound running faster so they sound different and take different timings to play - this was a common problem on systems that were popular in both countries like the C64.

5th Oct 2021, 6:00 pm	#45
Timbucus Octode Join Date: Mar 2019 Location: Barry, Vale of Glamorgan, Wales, UK. Posts: 1,364	Re: ZX Spectrum Issue 2 / new TVs This is a problem that affects all systems where the frame is tied to the display frequency - there are only a certain number of cycles available and less at 60Hz (as there are 10 more frames in the same second). If you say swapped a UK Issue 2 ULA with the US ULA and then tried to run some games that pushed the envelope they could well crash as they will receive an interrupt before they finish processing the previous one depending on how they are coded - it sounds like bikers read the available frame time and decided what to sacrifice - the advantage of a modern system and awareness of the frame frequency issue. That is why VGA-0 is ideal as it is exactly 50 frames a second. There is a similar effect where often the US experienced the games and sound running faster so they sound different and take different timings to play - this was a common problem on systems that were popular in both countries like the C64.