Review of the ANITA Mk 8

Below is a review of the ANITA MK 8 on its launch late in 1961[1].





    Not since 1874, when Willgodt Odhner perfected his barrel-type lever-set machine, has there been such a breakthrough in the field of desk calculators as Anita, which made its debut at the Business Efficiency Exhibition in October.
    British invented and designed, and manufactured by Sumlock Comptometer Ltd., Anita is an electronic desk calculator.  Thus calculations are done not only quickly but in complete silence.  The answers, with the correct decimal point indicated, appear in an illuminated dial.  Though this calculator has limitations, its price. £335 [GBP, about US$1000], is modest.

One Set of Dials

    The machine is extremely simple.  It has one register, two keyboards (one entry and one multiplier) with decimal-point keys, four instruction keys (— ÷ x +), two clearance keys (for the register and for the keyboard) and a non-shift lever (used for sterling addition).
    To learn to operate the machine is very easy.  To prove this we asked Sumlock Comptometer to train our 16-year-old typist who had never operated a calculating machine before and who has just an average school-girl's knowledge of arithmetic.

Invoicing After Two Hours

    After one hours instruction followed by one hour's experience to gain familiarity she could cope with straightforward calculations such as would be needed for invoice extensions and stock control.  The training was more concerned with the teaching of decimals than with the operation of the machine, but after two hours our pupil did, on Anita, the following calculations (given her without warning): 41¼ hours at 3s. 9d. per hour; £896 16s. ÷ 118 [this is the old British sterling £sd currency].  The multiplication took her about 10 seconds, the division twice as long.
    An experienced operator should learn to handle Anita within 15 minutes or so; her problem is similar to a typist getting accustomed to a new typewriter model.  After initial familiarizing, experience is required to obtain speed.  For example, the speed of adding depends merely on the rate at which an operator can key the digits.

Five Digits a Second

    We tested an experienced girl who added 10 numbers, five of two and five of three digits, in 5½ seconds.  This represented a keying speed of about five digits a second.  While adding (or subtracting) and multiplication on Anita is virtually instantaneous, division is a little slower.  To calculate the reciprocal of 7 to 12 places of decimals (the result capacity of the machine) takes just under five seconds.
    The entry capacity is 10 digits.  To add, the operator presses the + key and then enters the numbers (normally on the right).  To subtract she presses the — key instead of the + key.  The machine does not show a credit balance.
    To help a touch operator the tops of even keys are less concave than the tops of odd keys.  A touch operator will use only keys 1 to 5 to add because she can cover these keys with her span and finds it quicker to press two keys for digits greater then 5 than to move her hand.  Thus to enter 9 she keys 5 and 4.
    When the + or — key is pressed, the keyboard is automatically cleared after each entry.  When, however, the x key is down the entry keys remain down when pressed.  Below the entry keyboard is a row of decimal-point keys; the appropriate one is pressed and a light indicates the decimal point in a row of small windows beneath the result dials.  To multiply, after the multiplicand (with decimal point) has been entered on the main keyboard, the multiplier is entered in the column of 10 keys on the right.  The digits of the multiplier are keyed in sequence reading from left to right and the multiplier-decimal key (A) pressed when the decimal point occurs.  The product, with the correct decimal point indicated, appears instantaneously in the register.

Checking Both Factors

    There is no way of checking, though, that the multiplier has been entered correctly (the multiplicand can be checked for it remains set on the keyboard), so to check the multiplier the check-multiplier key (B) is pressed, whereupon the machine divides the product by the multiplicand and the result (i.e. the multiplier) appears in the register.
    Division on Anita is not so simple as the other operations, and two special rules are needed.  After the dividend has been entered on the left of the keyboard (by means of the + key) and the appropriate decimal-point key pressed, the decimal point must be moved one place to the left (rule No. 1).  Then the operator presses the ÷ key and enters the divisor on the keyboard.  She counts the digits to the left of the decimal point in the divisor and remembering this number counts the decimal keys to the left of the one already pressed and presses that decimal key (rule No. 2).

Large Divisors

    If the divisor is a large number there will be insufficient decimal keys to the left of the dividend's decimal point.  In this instance the operator carries on counting from the right of the row of decimal keys, and will include the cyphers appearing on the right of the register (and to the right of the decimal point indicated) before the remaining digits in the quotient (which appear on the left of the register).
    To add in sterling the usual method for rotary calculators is used.  Pence are added in the three columns on the right, shillings in the next three and £s in the left four columns.  To convert the pence to shillings and the shillings to £s, the x key is pressed and the non-shift lever (C) is pushed towards the operator so that it exposes a red indicator.  Then 988 (the complement of 12) is entered in the pence section and the appropriate multiplier key (or keys) pressed to convert the pence to shillings.  A similar procedure is carried out to convert the shillings to £s using the complementary number 980.

Telescopic Legs

    The machine is gracefully designed in grey and navy blue with the keys in two tones of light grey on a panel of dark grey.  At the rear of the machine are two 3-position telescopic legs which, when extended, tilt the machine to the convenience of the operator.  Measuring 18 by 15 by 9½in. high the machine is surprisingly light at 28lb. but unfortunately no handle is provided to facilitate carrying from desk to desk.  As yet Anita is not generally available, but orders will be taken as from 1 January, 1962.  Demonstrations of the machine, however, can be arranged by writing to Sumlock Comptometer Ltd., 39 St. James's, Street, London, S.W.1.


  1. "Simple and Silent", Office Magazine, Dec 1961, pp1244-1245.

The Bell Punch Company & the Development of the Anita Calculator
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