Dear all, I came across MUDBUG a monitor for the MC6800. It is much more “sophisticated” then MIKBUG and friends… I did find a report at a .gov website that shows the manual and schematics. Could not find anything on the website of Arizona State University which did a great part of the development. The question is if there is a) a S19 file, but rather the asm source code? It would be nice historically to add this to the legacy of mikbug, minibug, etc. Regards, Roland MUDBUG MUDBUG was a monitor and debugger program created for the Motorola 6800 by developers at Arizona State University in the mid-1970s. Designed as a resident system tool for low-level program control, MUDBUG provided early microcomputer users with interactive facilities to inspect, modify, and debug memory and registers. It exemplified the era’s shift toward software-based development environments for new microprocessors. Key facts Platform: Motorola 6800 Type: Machine-language monitor/debugger Developed at: Arizona State University Period: Circa mid-1970s Purpose: Memory and register examination, program testing, and I/O control Background and development MUDBUG emerged shortly after Motorola’s introduction of the 6800 microprocessor in 1974, a period when educational and research groups built tools to support the device’s use in embedded and teaching contexts. Arizona State University’s version extended the capabilities of Motorola’s own MIKBUG monitor, offering improved memory handling and command flexibility for laboratory instruction and small-scale system development.