On MC68000, 1010 EMULATOR and 1111 EMULATOR are exceptions. The former is generated when a program runs instruction $A000-$AFFF. The latter is generated when a program runs instruction $F000-$FFFF.
The 1010 EMULATOR, called "bad A-line instruction" in classic Mac OS, happens when the CPU executes an instruction whose opcode is $A000-$AFFF. Operating systems for computers with 68000 family CPUs, such as classic Mac OS, generally used this as a syscall mechanism. But a statically linked application not running on top of an operating system (such as a Sega game) might implement syscalls as direct subroutine calls and treat these as illegal opcodes.
The 1111 EMULATOR, called "bad F-line instruction" in classic Mac OS, happens when the CPU executes an instruction whose opcode is $F000-$FFFF. These opcodes were reserved for the
Motorola 68881 external FPU, which was eventually integrated into the 68040 CPU. If the FPU wasn't present, the CPU would throw an exception that FPU emulator software in the operating system could catch. If no emulator was installed, the operating system would terminate the application. Because classic Mac OS came out before the 68881, it didn't use an FPU emulator; instead, apps used a
software floating-point service in the operating system, and FPUs came with INITs (kernel extensions) that patched the floating-point service to use coprocessor calls. A program compiled for 68040, on the other hand, would use the hardware FPU directly and bomb with "bad F-line instruction" if it wasn't available.