Having the UI code in ROM doesn&#x27;t preclude (and might actually benefit) shipping a simple but versatile sort of debugging tool with the OS. But Apple decided against doing so, making the system more appliance-like overall.<p>DOS&#x27;s DEBUG isn&#x27;t just a debugger; it also functions as a disk editor, hex editor, memory inspector, and general &quot;system inspecting&#x2F;tinkering&quot; tool.