General Operating Instructions

Getting Started

Your HP-80 is shipped fully-assembled with battery pack in place and is ready to operate. Slide the power switch to ON. If anything other than 0.00 appears on the display, see Service, Appendix F
In the HP-80, arithmetic answers appear on the display immediately after pressing a +, , ×, ÷ key. In an adding machine, the + key adds the last entry to whatever is already in the machine, and the key subtracts this last entry. The HP-80 not only adds and subtracts the same way as the old familiar adding machine, it also multiplies and divides this way too—the × multiplies the last entry by whatever is already in the machine, and the ÷ key divides by the last entry.
The display blinks when logic or range errors are made. Whenever this happens, clear the display by pressing CLx; 0.00 appears on the display and a new problem may be entered.

Keyboard Description

Figure 1 illustrates the keyboard layout and classifies the keys according to type and function. Although most of the keys will be familiar to you, some require further explanation because of the unique features of the HP-80.

Number Entry Keys

Number Control Keys

Seven keys are provided for manipulating numbers:
  saves the number appearing on the display for arithmetic and basic calculations; terminates a number entry. (Pages 13 and 52.)
  rolls down and displays (in last-in/first-out order) whatever four numbers have been entered and are currently in the machine—one number with each press of the R  key. Permits review of previous entries or results. (Pages 16 and 54.)
  interchanges the last number previously saved with the number currently displayed; the former number reappears on the display. (Pages 17 and 54.)