miniasm is a short bytecode based assebler, interpreter and compiler
ZiLOG Z80 CPU emulation library
A disassembler and a simulator for the MSP430 CPU
The b0 Programming Language
powerpc disassembler/assembler
Java classfile assembler/disassembler and interactive low-level editor
Assembler language for modern times
The Basic Computer Assembler
Emulator and assembler