They said it couldn't be done. It's done. Doors CS v4.0 has been released, the first assembly version out of beta. All of the features are now fully operational and stable. Doors CS is an assembly language shell for the TI-83 that includes many advanced features for programmers, including icons for BASIC programs and icons and associated programs for assembly programs. It has a graphical user interface; the desktop and all sections of the shell can be navigated with the built-in mouse. Password protection, automatic low battery and low RAM detection, and even custom backgrounds are among the features in this edition. Doors CS v4.0 is available at http://www.ticalc.org/pub/83/asm/shells/doorscs83.zip.