GB1401265A - Variable function programmed calculator - Google Patents

Abstract

1401265 Calculator; keyboard and display TEXAS INSTRUMENTS Inc 27 June 1972 [19 July 1971] 44626/74 Divided out of 1401204 Headings G4A and G4H A calculator has a keyboard having a plurality of keys arranged in rows and columns, a plurality of output display devices, and a means for generating repetitive sequences of timing signals, each of at least some of said signals being connected to energize simultaneously a respective individual column of keys and a respective individual display device. The calculator is adapted for construction on a metal-insulator-semi-conductor integrated circuit chip and includes a read only program memory, a read/write arranged to provide a number of data registers for storing data serially by digit parallel by bit, and a binary or binary coded decimal serial by digit adder. The display elements may be light emitting diodes, liquid crystal devices, cold cathode discharge elements, fluorescent display elements &c., and as described are multisegment digit displays with coded segment select signals being applied to all the display elements one of which is selected by a timing pulse. The timing pulses and/or the coded segment selecting pulses may be truncated on their leading and trailing edges to prevent spurious displays due to "carry over" of the signals from one digit to the next. The keyboard is scanned by the timing signals, transient signals, e.g. due to keybounce, being overcome by scanning until a significant output is detected and re-sampling 1À5 msecs. later to distinguish a valid key operation. Instruction execution is generally conventional, an instruction address normally being incremented, there being provision for instruction address modification for conditional jumps in the program, or maintaining the same instruction address for "wait" instructions. An exemplary program is given.