The Tandy PC-5 Pocket Scientific Computer is a very useful and rugged machine. It has a palmtop design but is much smaller than the HP200LX. Another advatage of this unit is the hard metal case, this machine was built to last. It features scientific computing fuctions on the main keypad then has a QWERTY keypad on the upper half of the unit (under the screen). The Tandy PC-5 is also programable in either basic or assembly language as well as a memo function to store notes and misc information. If features an I/O port on the side and a single line alphanumeric LCD screen. The keys are soft rubber and are very comfortable to use, they are quiet and reliable when pressed. This device has replaced my expensive graphing calculator as a result of it's easiness to use/learn, it's comfortable feel, and it's BASIC programmability. Other features of the PC-5 include a hex calculator, buzzer, and its leight weight. Everybody needs one of these little wonders. I picked mine up for $5 but didn't have any documentation. If you have documentation forsale then please notify me.