i) Cross compiler:

• Cross compiler executes on one processor but generates code for a different processor
• Cross compiler is required to compile for multiple platforms from one machine
• Cross compiler is used to compile for a platform for which it is not feasible to do the compiling like microcontrollers which don’t support an operating system.
• The basic use of a cross compiler is to separate the build environment from the Target environment in embedded computers where a device has extremely limited resources or for compiling of multiple machines.

ii) Emulator:

• Emulator Emulates microcontroller inputs from sensors
• It emulates controlled outputs for the peripheral interfaces/systems
• It emulates target microcontroller inputs and socket to connect externally microcontroller unit

iii) Debugger:

• A debugger is a program that runs other programs which locates and fixes the errors in embedded system or C program code of an embedded hardware device.
• The debugger is able to examine program code and data during the execution of embedded program
• Most of the debugger also support functions such as single stepping execution ,addition of breakpoint at particular instruction and monitoring the vlaues of some or all variables.
• Some debugger have also the facility to modify the state of the program while running ,instead observe it and continue the execution at a different location in the program by ignoring a logical error.
• Debugger is also useful as a general testing verification tool test coverage and performance analyser. EXAMPLES ARE gnu, Eclipse etc in embedded systems

iv) In-circuit emulator:

• An in-circuit emulator (ICE) is a hardware device used to debug the software of an embedded system. It was historically in the form of bond-out processor which has many internal signals brought out for the purpose of debugging. These signals provided information about the state of the processor.
• An in-circuit emulator provides a window into the embedded system. The programmer uses the emulator to load programs into the embedded system, run them, step through them slowly, and view and change data used by the system's software.
• More recently the term also covers JTAG based hardware debuggers which provide equivalent access using on-chip debugging hardware with standard production chips.
• ICE’s attach a terminal or PC to the embedded system. The terminal or PC provides an interactive user interface for the programmer to investigate and control the embedded system.
• In usage, an ICE provides the programmer with execution breakpoints, memory display and monitoring, and input/output control