SPICE (Simulation Program with Integrated Circuit Emphasis) is a very popular and widely used simulator, principally for analog circuits but, in some implementations, for mixed-mode and even all-digital circuits. Some folks, Erik Malund apparently among them, just don't like and trust simulators. He's a programmer and knows what goes into software. SPICE is, after all, software.

For over 25 years, it has been the basis for detailed simulation and review of circuits throughout the industry. I doubt Bob Pease's remark was as global as Erik would like you to believe. There are occasions when SPICE yields "crap" but that's normally when the model it's using is "crap."

The Spice version you use is as important as the model. If you use a version tailored for one purpose, it may not work very well outside that realm. I'd suggest you try the "free" (demo" version of PSpice before wandering off into other versions, as it's a quite popular version in its commercial (quite costly) version. It is mixed-signal capable, and I'd also recommend you learn as much as you can about the digital simulation capabilities before using it, as it's sometimes only useable for a limited time, depending on where you got it.

LTSpice is good, too, and allows you to substitute more recent models, or versions of more recent silicon for what's in their library.

Spice simulators are plentiful and popular, mainly because they produce very useable results once you've figured out how to use them. SPICE is almost universally accepted, despite what Erik thinks. He doesn't like any simulation tools. I'd recommend you read the doc's before starting to play. It's best to know what your netlist is supposed to look like. That's particularly important for the stimulus specification.

I'm not aware of any current digital simulators that aren't associated with programmable logic of one sort or another. This is probably because there are so few digital components available that aren't programmable or highly-integrated and therefore model-less devices. I'd recommend you obtain the programmable logic tools freely available from Altera, Xilinx, and Lattice. Each of them has a simulator avaiable, and there's a ModelSim from Altera and one from Xilinx. I don't know whether Lattice has gotten ModelSim yet. Each has a "hobbled" version (goes slower than the paid-for version) avaialble at no cost, if they have one. I'd caution you not to be lulled into complacency by the Altera component libraries, which bear names of old-generation 74xxx TTL family logic, but don't always faithfully emulate their function. Their symbols leave a lot to be desired, too, if you plan to use schematic entry. Xilinx, too, has, for the past seven or eight releases had glaring errors in their component symbol libraries. One example is their tristate buffers. They show them as positive-enabled, but, in fact, their enables are active low. This can be maddening when you want a 74126-type and a 74125-type buffer in the same circuit.

As with any software tool, there are bugs and other forms of "gotchas."

Get a bottle of aspirin, a bottle of prune-juice, a bottle of MAALOX, and a bottle of whiskey, and you'll get through the process just fine. Oh ... a large monitor and a pair of appropriate reading glasses to help you see what's on it will help. I have a pair of "monitor-reading" glasses at each monitor. The guys who wrote the software didn't consider what a person using their work product needs, so they often show you 8 signals at the top of the screen with the rest empty, but no way to expand the scale vertically.

RE