Fixed screen bank color select in Forty-Love. Also fixed screen disable bit for Field Day / The Undoukai during transitions.

Got two easy gfx bug fixes yesterday, both related to background drawing:

* Fixed background breakable objects in 64th Street, it was caused by missing writes to a VRAM mirror.

* Fixed castle tiles not properly drawn in Sexy Parodius stage 3B (a.k.a. Castlevania / Akumajou stage). It probably need a blending effect for the mosaic windows tho:

Added dual screen support for Run N Gun: they used a multiplexer mechanism that sends signals at alternating intervals to each screen. What wasn’t obvious since now is that connected VRAMs were also bankswitched, and that was causing issues even in single screen mode because the supposedly unused sprite RAM is in reality used for internal gameplay state.

While fixing some sound related issues in WEC Le Mans 24/Hot Chase HW, I’ve got across a code snippet that was stealing a lot of cycles in Hot Chase. Turned out that Master CPU was checking for an hand-shake bit from sound CPU after sending a sound command data and an irq request line, and looping to a pretty fat chunk of time until eventually timing out if the default state is ‘1’ (which was default behaviour so far).  Fixing that, and gameplay speed finally normalized for good.

Recent improvements by Olivier Galibert and me regarding Top Landing / Air Inferno. Former can be considered working by now, latter is almost there.