Patent GB-1433117-A (GB)
Title: Programmable calculator
IPC: G06F7/00
Filed: 1972-12-20
Abstract: 1433117 Programmable desk top calculator HEWLETT-PACKARD CO 20 Dec 1972 [27 Dec 1971] 58867/72 Heading G4A A self contained electronic programmable desk top calculator has a keyboard for entry of alphameric data in the form of numerals, algebraic expressions (i.e., a, b ... x, y) and alphabetic messages. It includes a modular read-write and read-only memory unit capable of being expanded to provide the calculator with additional program and data storage functions, a central processing unit which performs both serial binary and pararallel binary-coded-decimal arithmetic, and an inputoutput control unit which bidirectionally transfers information between the memory or central processing unit and a number of input/output units. The memory, central processing unit, and input-output control units are controlled by a microprocessor included in the central processing unit. The input and output units include a keyboard input unit with a plurality of sections capable of being defined by plug-in read-only memory modules and stored programs added by the user, a magnetic card reading and recording unit which bidirectionally transfers information between an external magnetic card and the calculator, a solid state output display unit which displays every alphabetic and numerical character and many other symbols individually and in alphameric statements or messages. All of these input and output units are included within the calculator itself. An X-Y plotter, typewriter, a teletypewriter, a magnetic or paper tape reading and recording unit, and an extended read-write memory unit may also be employed. The calculator can be operated manually by the user from the keyboard input unit or automatically by a program stored within the memory unit to perform calculations and provide an output indication of the results. It may also be employed to load programs into the memory unit from the keyboard input unit, to separately collectively transfer data and programs bi directionally between the memory unit and an external magnetic card and to code programs stored in the memory units as being secure when they are transferred to an external magnetic card thereby preventing users of the calculator from retransferring them to an external magnetic card or obtaining any indication of the individual program steps once they are-reloaded into the calculator. In addition, the calculator may be employed to edit programs stored in the memory unit and to print out keystroke logs, program lists, labels, and messages. Absolute, symbolic, relative, and computed relative addressing may be employed. The calculator employs a high level keyboard language permitting the user to enter a line or one or more alphameric statements into the calculator from the keyboard input unit while visually observing an alphameric display of the line being entered check for errors therein, permitting the user to cause the entered lines to be immediately executed by the calculator and/or stored as part of a program within the memory unit, and permitting the user to subsequently recall the executed and/or stored line, so that it may be reinspected, re-evaluated and if necessary, edited and executed or reexecuted. Any entered or recalled line may be edited by employing the keyboard input unit to selectively delete or replace incorrect or undesired portions of the line or to selectively insert corrected or previously omitted portions of the line on a line-by-line or character-bycharacter basis. Syntax and execution errors are automatically detected by the calculator when they first occur and are indicated to the user via error messages dispalyed by the output display unit.  Circuitry converts each line entered into the calculator in the high level keyboard language into a post-fix polish code. It also employs an uncompiler for regenerating in the high-level keyboard language any entered line converted to the post-fix polish code. The compiler and uncompiler operate on a line-by-line basis. Divided out Specifications 1,433,118,1,433,119 and 1,433,120 have similar disclosure.