Updates for the latest versions of the C166, C251, and C51 tools have been posted to the KEIL web site at: http://www.keil.com/update Jon
but the release notes still don't tell us the difference between the latest version (v6.20) and the previous version (v6.14). In fact, the v6.20 Release Notes are virtually identical to v6.14, with just "14" changed to "20" wherever the version number is mentioned!