Flat Assembler is a fast and efficient self-assembling 80x86 assembler. It supports x86 and x86-64 instruction sets with MMX, 3DNow!, SSE up to SSE4, AVX, AVX2, and XOP extensions. It can produce output in binary, MZ, PE, COFF, or ELF format. It includes powerful but easy-to-use macroinstruction support and does multiple passes to optimize the instruction codes for size. It is written entirely in assembly language.
Yasm is a complete rewrite of the NASM assembler. It currently supports the x86 and AMD64 instruction sets, accepts NASM and GAS assembler syntaxes, outputs binary, ELF32, ELF64, COFF, Mach-O (32 and 64), RDOFF2, Win32, and Win64 object formats, and generates source debugging information in STABS, DWARF 2, and CodeView 8 formats.
WLA DX is yet another macro assembler that can program the GB-Z80, Z80, 6502, 65c02, 6510, 65816, HuC6280, and SPC-700 CPUs. Included in the package there is a GB-Z80 disassembler and few converters. WLA DX was initially programmed to compile ROM images for Gameboy, but nowadays it can also patch existing ROM images with code, and even compile program files and ROM files for other CPUs like the NES-6502, C64-6510, and SNES's SPC-700.
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.
J51 is a Intel MCS51 emulator with all the standard integrated peripherals. A disassembler with an integrated debugger is also included. Standard peripherals emulated are Timer 0/1 (Mode 0, 1, 2, and interrupts), serial interface in polled and interrupt mode, standard I/O, and ports 0 to 4. Microprocessors emulated are the Intel MCS 8051 (no peripherals), Intel 8051, Intel 8052, Philips LPC674, and Philips LPc900.
ProjectCenter is GNUstep's integrated development environment (IDE). It assists you in starting new projects and lets you manage your project files using a intuitive and well ordered graphical user interface. ProjectCenter automatically creates the project makefiles and aids you in the process of editing, project compilation, package building, and debugging.