SDCC is a Freeware, retargettable, optimizing ANSI-C compiler that
targets the Intel 8051, Maxim 80DS390, Zilog Z80 and the Motorola
68HC08 based MCUs. Work is in progress on supporting the Microchip
PIC16 and PIC18 series.

SDCC also comes with the source level debugger SDCDB, using the
current version of Daniel's s51 simulator.

WWW: http://sdcc.sourceforge.net/