DRYOS is an embedded real-time operating system developed by Canon for use in compact devices and employed in a wide range of company products such as digital cameras and digital video camcorders.
Source: Canon Inc.
“Event Shell is available on (almost?) all Cameras via UART connection. Look SD4000 for...Event Shell
“Since late 2007 Digic-based cameras are shipped using Canon's own Operating System named DryOS...DryOS Porting
“Canons firmware includes a scripting language, which appears to be a flavor of basic. Thanks to...Canon Basic/Reference