--- title: C64 Demo Effects Explained: Rodents in the Attic | daily.dev description: A detailed technical breakdown of a Commodore 64 demo called 'Rodents in the Attic', explaining the hardware tricks used to achieve seemingly impossible visual... canonical: https://daily.dev/posts/c64-demo-effects-explained-rodents-in-the-attic-cdxrm5uyg twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: C64 Demo Effects Explained: Rodents in the Attic | daily.dev og:description: A detailed technical breakdown of a Commodore 64 demo called 'Rodents in the Attic', explaining the hardware tricks used to achieve seemingly impossible visual... og:url: https://daily.dev/posts/c64-demo-effects-explained-rodents-in-the-attic-cdxrm5uyg og:image: https://api.daily.dev/og/posts/cDXrm5uyG.png og:image:alt: C64 Demo Effects Explained: Rodents in the Attic og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # C64 Demo Effects Explained: Rodents in the Attic **[Two Stop Bits](https://daily.dev/sources/twostopbits)** · 17 min read · 0 upvotes · 0 comments ## Summary A detailed technical breakdown of a Commodore 64 demo called 'Rodents in the Attic', explaining the hardware tricks used to achieve seemingly impossible visual effects. Covers how the VIC chip's border flags work and how to exploit them to open top, bottom, and side borders. Explains the 'ghost byte' hardware bug and how it enables high-resolution, multi-color lemming animations in the border area by combining ghost byte masking with per-raster-line sprite repositioning. Also details the extreme cycle-counting required to handle bad lines, sprite limits, and simultaneous side-border opening, including look-up tables and multiple code paths for each animation frame. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Help\! 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