The traditional In-Circuit Emulator (ICE) has in most cases been superceeded by the JTAG Emulator. Most recent microcontroller devices are fitted with a JTAG (or variants) interface which allows basic In-Circuit Emulation capability by the hosted debugger software communicating with debugger hardware within the microcontroller.
The JTAG Emulator is a much more cost effective solution that an ICE. However, it usually does not have ICE features such as emulation memory and multiple real-time breakpoints or Trace memory.
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