Calculator having merged key codes

• US 4,291,385 A
• Filed: 10/14/1977
• Issued: 09/22/1981
• Est. Priority Date: 12/17/1973
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Osborne, Thomas E., Stockwell, Richard K.
• Primary Examiner(s): Krass, Errol A.
• Application Number:
  US05/842,134
• Time in Patent Office: 1,439 Days
• Field of Search: 364/709, 364/706
• US Class Current: 708/146
• CPC Class Codes: G06F 15/02 manually operated with input through keyboard and computation using a built-in program, e.g. pocket calculators
• CPC Class Codes: G06F 15/0225 User interface arrangements, e.g. keyboard, display; Interfaces to other computer systems
• CPC Class Codes: G06F 3/0238 Programmable keyboards key guide holders G06F3/0224
• CPC Class Codes: H03M 11/04 Coding of multifunction keys
• CPC Class Codes: H03M 11/18 wherein the shift keys are operated before the operation of the multifunction keys

Abstract

A hand-held, programmable, electronic calculator is capable of performing a larger number of functions than the number of keys on its keyboard and has one or more prefix keys to allow one function key to initiate more than one function. Each key generates a unique key code when it is depressed, and the calculator may be programmed by storing a series of the key codes in a memory. Memory space can be saved by generating unique merged codes to represent the combination of a prefix key and a function key, and storing this single merged code rather than the two key codes.

Claims

1. A method for storing a sequence of instructions entered via a keyboard into a programmable electronic calculator, the method comprising the steps of electronically:

detecting the actuation of a key on the keyboard;

generating a key code representing the key actuated in response to the detection of the actuation;

deciding whether a status indicator has been set in a status register;

if no status indicator has been set, deciding whether the key code of the key actuated can be merged with a subsequently generated key code;

if it can be merged, setting a status indicator and storing the key code;

if it cannot be merged, storing the key code; and

if a status indicator has been set, deciding whether the key code of the key actuated can be merged with a previously generated and stored key code;

if it can be merged, generating a merged key code representing both the previously generated and stored key code and the key code of the key actuated, erasing the status indicator and the previously generated and stored key code, and storing the merged key code;

if it cannot be merged, storing the key code of the key actuated and erasing the status indicator.

2. A method of storing a sequence of instructions, entered via a keyboard having function and prefix keys, in a programmable electronic calculator, the method comprising the steps of electronically:

detecting the actuation of a key on the keyboard;

generating a key code representing the key actuated in response to the detection of the actuation;

deciding whether the key actuated can be prefixed;

if the key actuated cannot be prefixed, deciding whether the key actuated is a prefix key;

if it is a prefix key, setting a prefix status indicator and storing the key code;

if it is not a prefix key, storing the key code;

if the key actuated can be prefixed, deciding whether the key has been prefixed by looking for a prefix status indicator;

if it is prefixed, deleting the stored prefix key code and the status indicator, generating a merged key code representing the previously stored prefix key code and the key code of the actuated key and storing the merged key code;

if it is not prefixed, storing the key code and deleting the status indicator.