Portable Electronic Calculators

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Distinctive features:  The same as the AC only ANITA 1011 LSI but is a hybrid with an additional compartment at the rear with rechargeable batteries so that it can be used independently of the AC supply.  One example, illustrated below, has been modified by having the batteries removed and replaced by a capacitor for AC operation only.

Technical details:
Power supply - AC and rechargeable batteries (14x NiCad cells).

Display is 10 digits, Nixie tubes.

4- function, uses RPN (Reverse Polish Notation).

222 mm X 163 mm X 88 mm (9" x 6.5" x 3.5").

Made in England by Sumlock Anita Electronics Ltd., distributed by Sumlock Comptometer Ltd.

It has a leatherette-covered, wooden, fitted case.

Announced in late 1971[1].

Significance:  A portable electronic calculator with rechargeable batteries and built-in AC adaptor / charger derived from a purely AC model.

This was the first electronic calculator of Sumlock Anita Electronics capable of battery operation.  The introduction of the first hand-held model of the company was delayed because the managing director of the company could not see a market for it[2].

ANITA 1011B LSI in carrying case

Anita 1011B LSI in its fitted carrying case.

Battery bulge on ANITA 1011B LSI

The photograph above shows the bulge for the rechargeable cells on the back of the 1011B LSI.
Compare with the photograph below of the AC only model 1011 LSI.

ANITA 1011B batteries

Here the battery compartment at the rear has been removed and lowered down to reveal the 14 NiCad cells in three modules.  The cells appear to be a special size; each is 35mm long and 22mm diameter.

ANITA 1011B batteries replaced with capacitor

In the example above the NiCad cells have been discarded and have been replaced by the red capacitor (1500 μF, 25VDC) on the left which allows AC operation only.

Inside ANITA 1011B

With the cover removed showing the display and circuit boards of the ANITA 1011B LSI.

ANITA 1011B LSI inside

Here the small upper circuit board has been unplugged.  The integrated circuits by General Instrument Microelectronics (GIM) are contained in the five 12-pin cans, which are retained in holes in the circuit boards, and which would provide some extra physical support.  Note that, for reasons unknown, one hole is not populated.  The small grey rectangles with three leads are individual transistors.

The instruction sheet supplement with the ANITA 1011B LSI says:

"ANITA 1000 B & 1011 B

    The general usefulness of ANITA is now extended with the introduction of the Battery/Mains models.  These models can be used with or without mains current supply, so making them truly portable.  They have the battery and charging unit built in so as to make entirely self-contained units.

    All models are fitted with a Mains Connected Light – situated on top of the dark blue section, behind the display, at the left.  It illuminates when the machine is connected to a live mains power supply.

    The Battery Warning Light – symbolised by the letter "B" – is found on the extreme right hand side of the Display.  It illuminates only when the battery needs recharging.  The battery has a 4/6 hour continuous operation life.

    To recharge the battery ANITA should be switched to 'Off' and connected to a live mains supply.  The battery is only being recharged when the mains connected light is illuminated and, because the machine is switched 'Off', the display is unlit.

    In order to conserve battery life the display commences to 'blink' after approximately 13 seconds.  The figure displayed during the blinking operation is held by the machine and is available for further processing.  The blinking display serves as a warning that if the machine is not required for immediate use it should be switched off, when,

    Battery/Mains models retain the same operating advantages of the mains only models and the same Operating Instructions apply."


ANITA 1011 LSI Operating Instructions (pdf format).



  1. Management in Action, October 1971, p34.
  2. "The Rockwell Connection", http://anita-calculators.info/html/the_rockwell_connection.html

Vintage Calculators

Text & photographs copyright, except where stated otherwise, © Nigel Tout 2000-2024.