No ICE is completely satisfactory to everyone. No ICE is so inexpensive that one can buy it without considering the added benefit it provides very critically. No ICE is sufficiently documented that you can do that without first buying one or two and discarding them or selling them on eBay, a considerable loss. If you find one you like and that meets your needs, it's easy to become dependent on it, though.

If you have an MCU in an environment that allows you to use RAM as your program store, you can use a monitor to set breakpoints. Unfortunately, the 805x doesn't make this easy. A breakpoint would be set by substituting a break instruction for whatever instruction is at the desired location. When told to set a breakpoint, the monitor program substitutes a call to the breakpoint filter's common entry, looks at the return address stored on the stack and computes where the desired instruction is, and then does what it does, usually displaying status, register contents, etc, and allowing you to peruse/modify memory by some mechanism.

The ICE provides some of these abilities for you.

RE