Hand-held Calculators

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Novus 650

Novus 650 Mathbox

Novus 650 "Mathbox"

Distinctive features: Very basic calculator (has no decimal point key), with silicon chip mounted directly on circuit board.

Technical details:
Display is 6 digits, red LED.

4-function, fixed decimal point (2 decimal places), with calculations entered using RPN (Reverse Polish Notation).

Main integrated circuit - under blob of resin.

9v (PP3).

69 x 126 x 24 mm. (2.75" x 5.0" x 0.95").


Made in Malaysia.
for National Semiconductor.

An earlier version of this calculator is known with two integrated circuits in standard dual-inline packages.

Inside Novus 650 Mathbox

Inside, showing the small number of components.

Integrated circuit

The circuit board showing the blob of resin covering the integrated circuit chip.


The 6-digit LED display and the rest of the electronic components !

This calculator shows the minimalist approach in order to cut down on the manufacturing cost. Note how few electronic components it uses -

  • The display is only 6 digits.
  • The integrated circuit is not in a conventional package - it is bonded to the circuit board and protected by a blob of resin.
  • It has a fixed decimal point - set at two places of decimals, which is useful when calculating money values - so no "." key is needed..
  • It uses RPN (Reverse Polish Notation) calculation entry, so the integrated circuit needs less memory electronics and a "=" key is not needed.

National Semiconductor was another semiconductor company which produced calculators using its own integrated circuits and LED displays. A wide variety of models were sold ranging from this simple Novus 650 "Mathbox" to sophisticated programmable scientific, financial, and statistical machines. These were sold in the mid-1970s under both the National Semiconductor and the Novus names.

An article in the journal New Scientist in December 1976, refering to another calculator in this series, the 852, explained:
"Calculator technology has just taken one I further step—and pretty near the last— along the  road  to miniaturisation. National Semiconductor's latest scientific calculator contains no packaged integrated circuit ("chip") as we have come to know it. Instead of using the encapsulated  chip—in  a  dual  in-line assembly—the silicon microcircuit in this case is bonded on to the printed circuit board direct.

This technique has been used for some years now as far as light emitting diode (LED) arrays are concerned. Indeed, National Semiconductor pioneered the mass production of this technique in its latest clock modules.

In the company's new model 852 calculator, the keyboard is the largest component. The actual "works" are smaller than the PP3 battery that powers the calculator. Two chips are bonded on to the board, both housed under the black plastic protecting cap. One contains the scientific calculator functions—the other the drivers for the LED display. The light emitting diodes are also bonded to the same printed circuit board and are protected by magnifying lenses. This type of construction not only cuts costs but also increases reliability as there are relatively few interconnections."

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