Answer
The BT900 and BL600 documents refer to the UwTerminal utility which was the primary utility when these documents were written. This utility is still available in the firmware zip files when they are downloaded from the BT900 Product Page or BL600 Product Page .
However, UwTerminalX is the new improved version of UwTerminal offering additional features not available in predecessor UwTerminal. We recommend working with UwTerminalX as it will support all the features mentioned in the BT900 documentation and offer the additional features, such as access to online Xcompilers.
The latest release of UwTerminalX can be downloaded from our GitHub Repository: UwTerminalX/releases