<I'm getting this opinion straight from Ted Hoff himself. I don't know <where my notes are on this and I can't remember the details, but I think <there are some significant differences between the 4040 and 4004. The <8008 was supposed to have been based on the 4004 architecture, extending <it with more instructions and such. The 4040 was, I think, a whole <different design by a different team inside Intel. The 4004 and 4040 are very similar. the 4040 adds a few things like extra registers. The 8008 is really a 4040 stretched to 8bits. The 8080 is really pretty close to the 8008 though not object code compatable. I have the intel books on them so it's not like I didn't check. ;) Allison