This is an FKEY resource, which enables one to enter MacsBug by pressing -shift-0 (the zero on the top row of the keyboard). To make installing the FKEY easier I have ‘encapsulated’ it into a font suitcase. That way you can simply put it on your Fonts folder to install it. The custom icon and the Finder's get info box show that it isn’t really a FKEY.
Why to use it:
Firstly, it gives you a convenient way of entering Macsbug, which works on all Macintoshes. The advantage over other FKEYs which do the same thing is that this FKEY does not crash your Macintosh with an 'unimplemented trap' when you press it while no debugger is installed. The advantage over using -power on (on newer Macintoshes) or the interrupt button is that the FKEY is guaranteed to be called when the front application is the current process. Also, the interrupt button may be located at an inconvenient position. A disadvantage is that the FKEY is called only when the front process calls WaitNextEvent or GetNextEvent.
How it works:
It checks for the presence of absence of MacsBug by looking at the low-memory global MacJmp. If it is 0x00000000 or 0x80000000 it calls SysBeep, in all other cases it calls the _Debugger trap. This is (almost) the recommended way to check for the presence of MacsBug. For details see the source code.
Distribution policy:
This FKEY may be freely distributed, as long as this accompanying documentation and the source code are distributed with it.
