C64 Debugger by SLAJEREK/SAMAR is a Commodore 64 and Atari XL/XE code and memory debugger that works in real time.  It is a quick prototyping tool where you can play with Commodore 64 machine and its internals.

C64 Debugger embeds VICE v3.1 C64 emulation engine created by The VICE Team and Atari800 v3.1.0 emulation engine created by the Atari800 team.