The Remedy debugger was the first embedded system level debugger

Debugger

A debugger or debugging tool is a computer program that is used to test and debug other programs . The code to be examined might alternatively be running on an instruction set simulator , a technique that allows great power in its ability to halt when specific conditions are encountered but which...

 in the world. It offered many features that users take for granted today in the days when having a source level debugger was a luxury. Some of these features include:

• Multiprocessor operation
• Heterogeneous
• Distributed
• Dynamic thread view of the system
• Synchronized debugging for multiple threads
• Trace functions
• Operating system resource displays
• Source and assembly level debugging

It started as an academic research project (originally called Melody for debugging the Harmony Operating System). The results were published in a seminal paper on debugging multiprocessors systems.

The current version of Unison

Unison Operating System

The Unison Operating System is a real-time operating system optimized for system-on-a-chip , multi-core and digital signal processor systems. It is open source. It offers Linux compatibility while being much smaller than Linux...

continues to use both gdb and Remedy Debugger.