Debugging Area5150's "Lake" Effect: A Pixel-Perfect 8088 Emulator Saga

This article details the author's journey in debugging the "Lake" effect from the Area5150 demo within their IBM 5150 emulator, MartyPC, using a bus sniffer and decoder. Initially, the author confesses to using title-specific hacks to emulate the "Wibble" and "Lake" effects. However, by delving into the intricacies of the IBM CGA, particularly its lack of a vsync interrupt, the author overcame the challenges. The article thoroughly explains how dynamic clocking, scanline polling, and a custom vsync interrupt were leveraged to perfectly emulate the "Lake" effect. It shares various problems and solutions encountered during debugging, including precise modeling of CGA registers, timer interrupts, and DMA logic. Ultimately, MartyPC successfully runs the "Lake" effect hack-free, showcasing the brilliance of emulation technology and a passion for retro computing.