Fix inaccurate CIA timing in NTSC#930
Merged
ki-bo merged 1 commit intodevelopmentfrom Dec 30, 2025
Merged
Conversation
…er VIC-II raster instead of 63 #816
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Now correctly counting 65 cycles per VIC-II raster instead of 63.
Fixing issue #816
The frame_generator is by default configured to count 63 cycles per VIC-II raster. In case NTSC is used (D06F.7 and D06F.6 both clear), the default was not overridden with the correct NTSC cycle count (65). The PR aims to correct that. This should bring both the 1MHz CPU speed and the CIA timing in NTSC very close to the original C64 timing.