selecting the location in the ROM for read out of the next instruction. Input and output terminals are
provided for keyboard input, display output, timing signals, etc. A test mode of operation is provided
for quality control upon completion of manufacture of the chip. The test mode allows the entire ROM
to be tested by reading in addresses to the address register from external and reading out the
resulting word from the instruction register. During the test mode, normal incrementing and
branching of the address register may be externally inhibited.
3932846: Electronic calculator having internal means for turning off display
Inventor(s): Brixey; Charles W., Hartsell; Glenn A., Vandierendonck; Jerry L.
Issued/Filed Dates: Jan. 13, 1976 / Sept. 24, 1973
An electronic calculator system of the type having a keyboard input and a visual display is
implemented in MOS/LSI semiconductor chips having a data memory, an arithmetic unit, a
read-only-memory for storing instruction words, and control circuitry for operating the system in
response to keyboard inputs by selecting addresses for instructions from the read-only-memory, all
of which is located in monolithic semiconductor units. A technique is provided for turning off the
display after a selected time period by holding an instruction word in an instruction register while
repeatedly incrementing an address register for the ROM until it overflows, then branching to an
address defined in such instruction word. This is repeated until the selected time period is reached.
4115705: Electronic calculator with push-button on-off system
Inventor(s): McElroy; David J.
Issued/Filed Dates: Sept. 19, 1978 / June 14, 1976
An electronic calculator with a power supply ON-OFF arrangement actuated by momentary-closure
push-button switches which are part of the keyboard. A bistable latch circuit on the calculator chip is
continuously powered by the battery, and is caused to flip to an ON condition by actuating an ON
key, and this turns on a large, low-resistance transistor which is in series with the voltage supply
line going to all of the other electronic circuitry on the chip.
4208720: Calculator with algebraic operating system
Inventor(s): Harrison; Herman W.
Issued/Filed Dates: June 17, 1980 / July 26, 1976
Disclosed is an electronic calculator having a data entry unit for inputting numeric data, expressions
such as parentheses and hierarchal mathematical commands, an arithmetic unit for performing
arithmetic operations on the numeric data, a memory for storing the numeric data and associated
hierarchal mathematical commands inputted via the data entry unit and logic circuitry for enabling
the arithmetic unit to perform arithmetic operations on numeric data inputted via the data entry unit
within a pair of parentheses, the logic circuitry enabling the arithmetic unit to perform a higher order
hierarchal mathematical command before a lower order hierarchal command even though the
higher order command is received after the lower order hierarchal mathematical command.
4348733: Calculator with algebraic operating system
Inventor(s): Harrison; Herman W.
Issued/Filed Dates: Sept. 7, 1982 / Nov. 19, 1979
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