Well I own a TI-86. It does everthing I need it to. Although I'm sure having an 89 or 92 would rule. If the HP49 does that damn reverse calculation **** then no thank you. I'll stay with good ol' normal calculatin' TI's.
The 86 and 89 have a solve function on them. Try to find that on the 83. I don't know if it has it though.
I have a TI-83 Plus as well and it is a good calculator especially because that's what most of the teachers use to teach. The answer to your question is no they do not but if you go with a TI-89 and up they will.
TI 92 is a bad mofo. I had mine four years ago and the ability to solve simulateous equations quickly and symbolic integration rocks on chemical engineering tests.
DoD, unless I'm smoking crack rock you originally said HP 46. I remember this cuase I thought it was odd at the time but I looked it up and HP did actually make a 46 model. The reason I bring this up is cause I'm pretty sure you edited the post toay HP 48 but there is no "last edited on such and such date" tag at the bottom of your message. Am I imagining things when I remember you originally saying HP-46 or is there some supersecret way to avoid the "last edited" tag?