Digital Signal Processing Block Diagram Compiler - user extendable to all DSP's, but presently supports only the TI C2000 family. Rich support for fixed point arithmetic, both saturated and unsaturated. Block diagram entry is via TinyCAD (included).
Thanks to carefully thought out architecture an emulator for all hardware (i386 i860 sparc hppa SGI Mips Alpha etc) on any hardware. A lot of new theories have gone into this trying to fix old problems.