The following are links to the TI website where you can download your calculator's manual.
TI-83 Guidebook
TI-83 Plus Guidebook
TI-83 Plus Silver Edition Guidebook
TI-89/TI-92 Plus Guidebook
Other unlisted TI calculators
All files below are in .pdf format. If a .pdf file does not display correctly when it is viewed inline with the Acrobat Reader plugin, then download it to disk and open it directly.