Section 1

General Operations

In this section we will describe how to:
  perform the clear operations
  control the display
  enter numbers in scientific notation
  recover from wrong keystrokes using the Last X feature.
In addition, a reference block is devoted to the operation of the Stack Lift (automatic enter).

Clear Operations

Four separate clearing operations are possible with the HP-65, using the f functions of the fourth row of keys.

Clearing Unwanted Prefix

fPREFIX cancels the effect of a prefix so that a non-prefix operation can be done. Let’s say you accidentally press f, f-1, or g, before keying in a number. If you then press the number key, you will get an alternate function of that key instead of the desired number-entry operation. To prevent this from happening, press fPREFIX to cancel the effect of the unwanted prefix key, then key in a number. If a wrong prefix key is pressed when another prefix is wanted, the error can be corrected by simply pressing the correct prefix and proceeding from there.
The above procedure can also be used to clear the following keys (not yet explained):

Clearing Stack Registers

fSTK clears all four registers (X, Y, Z, and T) of the operational stack. To clear only the X-register, press CLx.

Clearing Addressable Registers

fREG clears all nine addressable registers. (These will be described in a later section.)