On NoIce site you could read :
# Enough EPROM to hold the monitor (about 1024 bytes; smaller than most stand-alone monitors).
# Enough RAM to hold the monitor's data (32 to 256 bytes, depending on the number of processor registers and the desired communications buffer size)
# A UART to communicate with the PC host (or an input bit, an output bit, and the appropriate user-provided bit-banging serial code)
# Enough RAM to hold the program to be downloaded and debugged. If the processor distinguishes between code and data space (e.g., the 8051 or the Z8), then hardware external to the processor is required to allow the program space to be read and written by the processor. On the 8051, this usually means circuitry to OR together PSEN and RD, and to connect WR.
# Special hardware to support single step operation is not required.
Bye !