Nonpareil is a microcode-level simulator for HP calculators introduced between 1972 and 1982, including the HP-35, HP-45, HP-55, HP-25, HP-34C, HP-38C, HP-41CV, HP-11C, HP-12C, HP-15C, HP-16C, and other models. The necessary microcode is included, as is a microcode assembler. The GTK+ toolkit is used for the user interface.
avrLab tries to be an complete IDE for the AVR microcontroller chips from Atmel. It offers an editor with syntax highlighting which has standard editor commands like copy, cut, paste, goto line, search, and replace. Additionally, it includes support for tavrasm (a compiler for the AVR assembly language), uisp (used for the communication to the AVR), and much more.
asfpga is an assembler written for use in FPGA design. It can be easily modified for a particular instruction set. The ultimate goal of this software is to allow a FPGA designer to easily write assembly code for a custom instruction set. The current version allows you to create a listing file, a memory dump file which can be used in debugging HDL code using $readmemh() or equivalent routine, and a binary file which can be used to program an EPROM.