My dear friend Johan Borg has released a new text about the inner workings of the ti89. It is some old from texts he have written before and some new. you find it at: ftp://d188.ryd.student.liu.se/calculator/ti89/tech/89hw.txt Anyone interesting in tweeking max out of your 89 programming should be interested in reading this manual. Can also be useful for hardwarebuilders. //Olle