The 2.6.6 release is mainly a maintenance update for the mappers and emulation core with a few new features added in. Some of these new features apply only to the Qt/SDL version of the GUI. Common Mappers

• Minor refactor of the save game RAM code. Fixes UNROM-512 flash clearing bug during movie play.
• Mapper 354: Add CHR-RAM protect.
• Mapper 78: Add submapper support.
• Added mapper 174 support.
• Move mapper 205 to mapper 361/366, added proper mapper for 205.
• Mapper 205: Fix for split-rom variant (UNIF)
• Changed UNROM-512 to use 8kB of CHR-RAM memory by default.
• Mapper 342 memory optimization.

 LUA

• Implemented LUA function memory.registerread.

 Core

• Memory initialization settings are now also applied to nametable, palettes, and sprites.
• Fixed bug were write instructions didn't always update the databus.

 Qt/SDL Debugger

• Added ld65 debug file symbol loader feature.
• Added checkbox to Qt debugger menu to control trace logger auto start function on debugger open.
• Added code to stop the trace logger on debugger close if it was the debugger who started it in the first place.
• Added address validity checking to the breakpoint editor dialog entry fields.

 Video

• Added a third video driver option that uses a QPainter object to render QImages to the viewport (uses a pure Qt API).
• Fixed video transparency issue that has been seen on some platforms (Wayland) by forcing alpha bits to be set to full opaque.

 GUI

• Added state recorder feature, periodically saves time history of game play states that can be recalled and played out from.
• Fixed bug regarding force grayscale or use custom palette settings change not updating PAL 3x filter appropriately.
• Added feature that allows loading of save state files via drag n drop file dialog operations.
• Fixed redundant window focus bug that would occur when attempting to open a pre-existing window.
• Added optional cross-platform libarchive interface to allow Qt GUI to open ROMs from 7zip archives.
• Minor improvements to the ROM selection from archive dialog.
• Improved frame scheduling timing precision.

 Build

• Build fixes for GCC 13.