Rowley Crossworks for ARM and SEGGER Embedded Studio are lacking support for assorted microcontrollers.
This is a collection of unofficial CPU support packages for some such microcontrollers.
Most users will likely just want to download the Rowley .hzq / SEGGER .emPackage files from the Releases tab near the top of this page.
Installing a package manually in Rowley Crossworks for ARM is straightforward: Choose Tools -> Packages -> Manually Install Packages.. from the pull-down menus, and pick your .hzq file of choice.
Installing a package manually in SEGGER Embedded Studio is also straightforward: Choose Tools -> Manually Install Packages.. from the pull-down menus, and pick your .emPackage file of choice.
The source code is also provided to show how custom CPU support packages can be done. Note that whilst Rowley Crossworks for ARM can generate packages for both tools, it appears that SEGGER Embedded Studio can only generate packages for itself. When generating Rowley .hzp packages, be sure to compile the Loader in the "Release" configuration before building the package.