Once logged on, select Downloads. Within the Downloads page, under Development Tools, select Development Studio 5 (DS-5). Within the right hand side column of the Development Studio 5 page you will find the latest ARM Compiler update release for Windows and Linux. Select the required version and follow the download instructions. Older versions of ARM Compiler updates can be found by expanding the Display older versions link.
For those who just want to browse the release notes, you can find them on ARM Infocenter. From the main page, select ARM Software development tools. Expand ARM Compiler toolchain. Expand the version of the compiler you are interested in, then choose the relevant release note.