John Wolff's Web Museum

The Bell Punch Company - PLUS, Sumlock, and Anita


 

Contents

Sumlomatic
Sumlock "Sumlomatic", c.1960

Overview

The Bell Punch Company (BPC) was established in London in 1878, and took its name from its original product - a tram conductor's registering ticket punch. The company expanded into ticket printing and issuing equipment for trams, buses, and cinemas, racecourse betting tickets, and taxi meters. Their activities were generally related to "cash control systems", and were coordinated through a holding company "Control Systems Ltd" from 1927. Both companies established branches in Australia and other Commonwealth countries.

In 1936 the company purchased the rights to a small half-keyboard adding machine which was sold as the "PLUS Rapid Adder". Larger full-keyboard versions with Comptometer-style safety mechanisms were marketed under the name "Sumlock". The London Computator Corporation was established in 1940 to handle the calculator business, but the nameplate soon reverted to The Bell Punch Company.

The PLUS and Sumlock machines were very popular in Britain and Commonwealth countries. They continued in production for almost 40 years, until replaced by computers and electronic calculators in the 1970s.

In the late 1950s the Bell Punch Company acquired the British rights to the Comptometer name from the ailing Comptometer Corporation (formerly Felt & Tarrant) of Chicago. When Comptometer production ended in 1961, the Bell Punch Company exported re-badged Sumlock machines to America to be sold as new-model Comptometers.

In the mid-50s the company started to introduce electronics into its product lines, and began work on an electronic calculator. The world's first commercial electronic calculator, the Sumlock "Anita", was introduced in 1961. The Sumlock Anita Electronics Company was established in 1966 to handle the calculator business (including the mechanical calculators), but was taken over by the American Rockwell organisation in 1973. Rockwell soon lost interest in calculators in favour of their aerospace business, and Sumlock Anita was effectively disbanded in 1976. The Bell Punch Company continued on with its traditional ticketing products, until it too was finally broken up and sold in 1986.


The PLUS Rapid Adder

The original mechanism of the PLUS Rapid Adder was designed by Guy Petter of the Petter oil engine family during the 1920s. The design was acquired by the Bell Punch Company in 1936, and was put into immediate production. A greatly improved mechanism was developed by Christopher Webb of Bell Punch in 1938, and formed the basis of all subsequent models.

The PLUS adder is generally found as a half-keyboard machine with keys from 1 to 5 only, although full-keyboard versions were also made. It was common practice among skilled Comptometer operators to use only the lower half of the keyboard for addition, as it was found to be less tiring to enter (eg) 8 by striking 4 twice, than to move one's whole arm to make a deeper and firmer stroke on the 8 key. The half-keyboard machines were much smaller, lighter, and cheaper than the full-keyboard models, and were entirely satisfactory provided one had no need for anything beyond simple addition.

The internal mechanism of the PLUS adder was quite different to both the Comptometer and the Burroughs Calculator, and provided a reasonable degree of error protection. The machine would not register if a key was not fully depressed (although there was no error indication or lockout), and would not repeat a keystroke until the key had fully risen. A latching mechanism on the clearing lever provided a definite start-from-clear signal.

Click on the photos below for larger illustrations.


Plus Bakelite (8kb) Bell Punch "PLUS Rapid Adder", Model A, S/N 3,332
9 columns, Sterling currency (no farthings)
Dimensions: 8-1/2"W x 6"D x 4"H
Weight: 5 pounds
Manufactured: Bell Punch Company, England, 1936-

This first version of the PLUS Rapid Adder (Model A) was housed in a black bakelite case. The PLUS name and the manufacturer appear only in a small circular badge or roundel set into the rear of the case.

The nameplate on the base of the machine lists three of the US patents that were filed by Guy Petter from 1923 to 1931.The mechanism operates on the downwards keystroke, with the register advancing in proportion to the depth of travel. A "duplexing " mechanism allows keys in adjacent columns to be operated simultaneously, but there is no protection against incomplete keystrokes. The clearing lever on the right-hand side is pushed downwards to advance the register dials to zero.


Plus early Sterling (9kb) Bell Punch "PLUS Rapid Adder", Model 509/S, S/N LC/509/S/3,774
9 columns (10 digits), Sterling currency (no farthings)
Dimensions: 9-1/4"W x 7-1/2"D x 5"H
Weight: 9 pounds
Manufactured: London Computator Corporation, England, about 1940

A 9-column PLUS adder for Sterling currency, produced by the London Computator Corporation in about 1940. The mechanism sits on a flat steel baseplate with substantial rubber feet, and has a grey die-cast cover with moulded lifting handles. There is a gold "Bell Punch" transfer on the front, with the PLUS name formed from individual metal letters. There are movable decimal indicators along the front of the viewing window.

The revised mechanism in this (and subsequent) machines operates on the upwards stroke of the key, and provides protection against incomplete keystrokes in both directions. The small clearing lever on the right-hand side has a very short movement. It remains latched in position until the first keystroke of the next calculation to provide a "start from clear" indication. The numeral wheels return backwards to zero when the clearing lever is operated.


Plus 512 Sterling (8kb) Bell Punch "PLUS Rapid Adder", Model 512/F, S/N 512/F/90,075
12 columns, Sterling currency (with farthings)
Dimensions: 11-1/2"W x 7-1/2"D x 5"H
Weight: 11 pounds
Manufactured: London Computator Corporation, England, 1940s

A 12-column PLUS adder for Sterling currency, with farthings, in a plain dark-green case. The Bell Punch transfer is rather faded, and the glued-on PLUS letters have all fallen off.

The PLUS machines were made in versions with 6, 9, and 12 columns. They could be supplied for Sterling currency (with or without farthings), decimal currency, feet and inches, hours, minutes, and seconds, and even tons, hundredweight, and quarters.

The model numbers show the number of keys and columns (5-09, 5-12, etc), the denominations (S for Sterling, F for farthings, C for decimal, etc), and a consecutive serial number (although the 90,000 number on this 1940s machine appears to be well out of sequence).


Plus 506 Sterling (8kb) Bell Punch "PLUS Rapid Adder", Model 506/S, S/N 506/S/43,769Q
6 columns, Sterling currency (no farthings)
Dimensions: 7"W x 7-1/2"D x 5"H
Weight: 6-1/2 pounds
Manufactured: Bell Punch Company, London, 1950s

A compact 6-column PLUS adder for Sterling currency.

The PLUS machines from the 1950s had a medium green hammertone finish and a re-styled metal clearing handle. The individual glued-on letters forming the "PLUS" name have been replaced with a one-piece badge.


Plus 509 (converted) Bell Punch "PLUS Rapid Adder", S/N 509/F/206,186L
9 columns (10 digits), converted to decimal currency
Dimensions: 9-1/4"W x 7-1/2"D x 5"H
Weight: 9 pounds
Manufactured: Bell Punch Company, England, late 1950s

The Bell Punch Company made frequent minor changes to the details of the PLUS machines. This late-1950s version has an aluminium baseplate, with the mechanism and the cover both mounted on rubber bushings. The Bell Punch transfer and the decimal point indicators have been deleted from the front panel, and the keytops have changed to round instead of the previous octagonal. This machine was originally built for Sterling currency, but was re-built in decimal during Australia's currency conversion in 1966.


Plus late green (8kb) Bell Punch "PLUS Rapid Adder", S/N 509/S/853,654
9 columns (10 digits), converted to decimal currency
Dimensions: 9-1/2"W x 7-1/2"D x 5"H
Weight: 7 pounds
Manufactured: Bell Punch Company, England, early 1960s

A late-model Plus adder in a re-styled case, incorporating a light-weight die-cast baseplate with inbuilt lifting grips. The cylindrical keytops extend through individual holes in the one-piece top cover. The PLUS badge has been moved to the rear panel, replacing the original embossed circular badge, and the clearing handle has been relocated to the top front corner of the machine. The pressed-metal gears in the register and carry mechanism have been replaced with moulded plastic, but the mechanism is otherwise identical to the earlier models. This machine was originally built for Sterling currency, but was converted to decimal in 1966.


Plus 509 late decimal (8kb) Bell Punch "PLUS Rapid Adder", S/N 509/C/859,127
9 columns (10 digits), decimal currency
Dimensions: 9-1/2"W x 7-1/2"D x 5"H
Weight: 7 pounds
Manufactured: Bell Punch Company, England, mid to late 1960s

The final version of the Plus adder was finished in a colour that varies from beige to pink, depending on the light and the time of day. This machine was factory-built for decimal currency.


Plus 509 for Imperial weights Bell Punch "PLUS Rapid Adder", S/N 509/Z/857,418
9 columns (10 digits), Imperial weights
Dimensions: 9-1/2"W x 7-1/2"D x 5"H
Weight: 7 pounds
Manufactured: Bell Punch Company, England, mid to late 1960s

This Plus adder was factory-built to calculate in Imperial weights, from 1 ounce to 10,000 tons. The Imperial system involves 6 units and six different number bases. One ton of 2240 pounds is divided into 20 hundredweight (abbrev. cwt) of 112 pounds each. The hundredweight is divided into four quarters (qrs) of 28 pounds, and the quarters were divided into two stones of 14 pounds. The pounds (lbs) are divided into 16 ounces (oz). Hundredweight were generally used for heavy bagged goods (cement, stock feed, etc - 20 bags to the ton), stones were used to express weights of people, while pounds and ounces were in general and domestic use.

From the right, the columns on this machine are:


Plus converted (8kb) Bell Punch "PLUS Rapid Adder", S/N 509/S/68,355
9 columns (10 digits), converted to decimal currency
Dimensions: 9-1/4"W x 7-1/2"D x 5"H
Weight: 9 pounds
Manufactured: Bell Punch Company, England, 1950s

Australia's decimal currency conversion in the mid-1960s presented a number of problems for the earlier PLUS machines. Most of the mechanism parts were still available from the factory, although the gears were now being made in plastic rather than metal. Octagonal and round keytops were no longer available, and there were difficulties in matching the colours of the green cylindrical keys. Converted machines will generally be found to contain a mixture of parts from different sources, sometimes including parts stripped from "trade-in" or recycled machines. The colour groupings in the keyboard and registers did not always match the factory originals.



The Sumlock comptometer

During the 1940s Christopher Webb of The Bell Punch Company developed a line of full-keyboard key-driven machines based on an extended version of his improved "Plus" mechanism. The name "Sumlock" was applied to these later machines which included a Comptometer-style locking mechanism to guard against incomplete keystrokes. If a key is not fully depressed, the entry will not register, the key will not rise, and the rest of the keyboard will immediately lock. The operator can complete the keystroke on the conspicuous half-risen key, clear the lock by pressing the release lever, and continue with normal operation.

The Sumlock machine also has protection against incomplete upstrokes, and includes a start-from-clear signal and cutoff levers for use in subtraction. The machine is functionally equivalent to the Felt & Tarrant Comptometer, although based on an entirely different mechanism.

Webb continued to develop the Sumlock machine during the 1950s, adding an electric motor drive, a second "grand-total" register, and finally a semi-automatic multiplier mechanism.

In the late 1950s the ailing Comptometer Corporation of Chicago sold the British rights to the Comptometer name to the Bell Punch Company, and imported Sumlock machines to America to be sold as new-model Comptometers. The machines were branded "Sumlock Comptometer" in Britain, "Sumlock" in the BPC export markets, and in "Comptometer" in America. The machines reached Australia through both the Bell Punch and the Felt & Tarrant distributors, resulting in two competing lines that were identical in all respects, apart from the name badge and the colour scheme. (Compare the machines below with those on the Felt & Tarrant page).


Sumlock 912 Sterling (8kb) Sumlock comptometer, Model 912, S/N 912/S/104,673
12 columns (13 digits), Sterling currency (with farthings)
Dimensions: 12-1/2"W x 13"D x 6"H
Weight: 17 pounds
Manufactured: Bell Punch Company, England, 1940s

An early 12-column Sumlock comptometer for Sterling currency, with farthings, but with no 10 or 11 keys in the pence column. The practice of using multiple keystrokes made the keys unnecesary for addition, but their absence did introduce some minor complications in subtraction.

The machine is based on the improved PLUS mechanism, which has been extended to provide Comptometer-style error detection and keyboard locking. The lock release is via the small red button at the right-hand rear.


Sumlock 912 Sterling (8kb) Sumlock comptometer, Model 912, S/N 912/S/4A/130,611
12 columns (13 digits), decimal currency (converted)
Dimensions: 13"W x 12-1/2"D x 6"H
Weight: 17 pounds
Manufactured: Bell Punch Company, England, 1950s

A 12-column machine from the 1950s, in a re-styled casing with new cylindrical keytops.

The clearing lever has been relocated to the front right corner, and now performs two separate functions. It is drawn forward to clear the register, or pushed rearward to clear the keyboard lock.

This machine has been converted from Sterling to decimal currency.


Sumlock dual register (8kb) Sumlock dual-register comptometer, Model 912, S/N 912/S/Va/510,003B
12 columns (13 digits), Sterling, dual register, electric
Dimensions: 13"W x 13"D x 8"H
Weight: 29 pounds
Manufactured: Bell Punch Company, England, 1953-

A 12-column machine for Sterling currency (no farthings), with an electric motor drive and a second "grand total" register at the rear.

The powered driving mechanism is described in Webb's US Patent 2756932, and the dual register in 2773647, both filed in 1951.


Sumlock FigureFlow (8kb) Sumlock "Figure-flow" comptometer, S/N 909/IVB/C/143,875
9 columns (10 digits), decimal currency
Dimensions: 10-1/2"W x 13"D x 6"H
Weight: 14 pounds
Manufactured: Bell Punch Company, England

A 9-column "FigureFlow" comptometer in a re-styled casing. There were no significant changes to the mechanism.


Sumlock Duolectric (8kb) Sumlock "Duolectric" comptometer, Model 912, S/N 912/VZ/C/915,277
12 columns (13 digits), decimal, dual register, electric
Dimensions: 13-1/2"W x 14"D x 8"H
Weight: 29 pounds
Manufactured: Bell Punch Company, England

A 12-column dual-register machine for decimal currency in a re-styled casing, now labelled as the Sumlock "Duolectric".


Sumlomatic (8kb) Sumlock "Sumlomatic" comptometer, Model 912/F/VIa, S/N 607,490A
12 columns (13 digits), dual register with multiplier, electric
Dimensions: 14"W x 15-1/2"D x 7-1/2"H
Weight: 35 pounds
Manufactured: Bell Punch Company, England, 1959-

The "Sumlomatic" was the final development of the Bell Punch Company's mechanical calculators. It is based on the motor driven dual-register machine, with the addition of a third register and a control mechanism to perform semi-automatic multiplication. The concept is described in Webb's US Patent 2956741, filed in 1955, but the machine did not reach the market until 1959. The Sumlock "Anita" electronic calculator was announced in the following year.

The machine illustrated was originally built for Sterling currency, with the multiplier register covering the Pounds (ie, decimal) columns only. It was converted to decimal currency in 1966, but the multiplier register was not extended. All-decimal machines with full-width multipliers were also made.
All-decimal Sumlomatic, from a book of tables dated 1959.



The Anita electronic calculator

The Bell Punch Company is generally credited with building the first production electronic calculator - the Anita - in 1961. The first Anita was a full-keyboard machine which was similar in form and function to the existing Sumlock mechanical comptometers, with the logic circuits based on cold-cathode vacuum tubes. A range of 10-key, all-solid-state machines (the 1000 series) was introduced in 1969, followed by an IC-based 1000-LSI series in 1971. IC-based pocket calculators were made from 1972 until the operation was disbanded by the new owners (Rockwell) in the mid-1970s.


Anita 1000 Anita 1000 Series, Model 1000, S/N 2335
Functions: ASMD
Technology: Discrete-component DTL, 5 IC chips
Display: 10 digits, Nixie tubes
Dimensions: 265W x 335D x 175H, weight 5.8kg
Manufactured: Bell Punch Company, England, 1969-72

This 10-key Anita Model 1000 is a basic 4-function machine which was made in England in early 1970. The machine is built almost entirely with discrete-component logic, using hundreds of individual resistors, diodes, and transistors. The components are mounted on a total of 20 circuit boards, each 230mm (9") wide by 2, 3, or 4" high.

Because of the very limited processing capability of these early machines, several manufacturers (including Anita and Hewlett-Packard) adopted the postfix (or "reverse Polish") logic system in order to simplify the internal circuit design. This system shares the workload by requiring the operator to enter the problem in a sequence that is more easily digested by the calculator. Although initially unfamiliar, the postfix system is entirely logical and rather elegant, and it aquired many supporters amongst scientific and technical enthusiasts. It was eventually abandoned in favour of "algebraic" logic as calculator capabilities improved, but is still widely used in some computer programming languages.


Anita 1011 Anita 1000 Series, Model 1011, S/N M2971
Functions: ASMD, constant, percent, roundoff, 1 memory
Technology: Discrete-component DTL, 7 IC chips
Display: 10 digits, Nixie tubes
Dimensions: 265W x 335D x 175H, weight 5.9kg
Manufactured: Bell Punch Company, England, 1969-72

The Anita Model 1011 is a similar but more capable machine which includes percentage calculations, 2-digit roundoff, and a memory or "Store" function. Other models were available with a square root function or an internal printer.


Anita 1011-LSI Anita 1000-LSI Series, Model 1011-LSI, S/N LM 107206
Functions: ASMD, constant, percent, roundoff, 1 memory
Technology: LSI, 5 IC chips
Display: 10 digits, Nixie tubes
Dimensions: 225W x 140D x 90H, weight 1.0kg
Manufactured: Bell Punch Company, England, 1971-

This Anita Model 1011-LSI from 1971 is functionally equivalent to the Model 1011 (above), but has been reduced to less than a fifth of the size and weight. The circuitry is based on five custom-built LSI (large-scale intergration) metal-can ICs from General Instruments Microelectronics. The distinctive styling incorporates the same full-size Nixie-tube display as the 1011, with a "wrap-around windscreen" borrowed from many of the cars of the 1960s.


Adler 84F Adler Financial Calculator, Model 84F, S/N 68.828.401
Functions: ASMD, percent, financial calculations
Technology: MOS-LSI (Rockwell A4561PB)
Display: 8 digits, vacuum fluorescent module
Dimensions: 75W x 120D x 20H, weight 200g.
Manufactured: for TA Vertriebs GmbH, Nürnberg, Germany, 1975

A range of Anita pocket calculators was designed and built in England from 1972. The same machines (with different colour schemes) were also supplied to Triumph-Adler in Germany, and were sold under both the Triumph and Adler brands. The sides and back of these Anita calculators are formed from a distinctive one-piece metal sleeve which slides upwards to open the battery compartment.

This Adler 84F from 1975 is a variant of the Anita 861 calculator for business and financial applications. In Algebraic mode it performs only ASMD and percentage calculations, with all results rounded to 2 decimal places. In Business mode it performs pre-programmed financial calculations involving prices, payments, and interest, with assistance from the Enter and Compute keys. The circuit boards appear to have been made in Japan, to a British design, for sale by a German company - but both the British and German companies were owned by Americans! (Triumph-Adler was owned by Litton Industries from 1968, and Sumlock Anita was owned by Rockwell from 1973).


Rockwell Model 18R Rockwell LED Calculator, Model 18R, S/N 354123
Functions: ASMD, percent, 1 memory
Technology: MOS-LSI (Rockwell B5000CC)
Display: 8 digits, NS LED module
Dimensions: 75W x 155D x 22H, weight 160g.
Manufactured: Assembled in Mexico for Rockwell International, Anaheim, CA, 1976

The 18R is one of a family of LED-display calculators produced by Rockwell under their own name in the mid-1970s, shortly before they abandoned the calculator business. The machine illustrated was assembled in Mexico using "US and foreign parts". Others are known to have been assembled in England at the former Sumlock Anita factory.

The circuit board uses a Rockwell B5000CC processor and an 8-digit LED display panel from National Semiconductor. The calculator draws only 7 to 30mA (270mW max) from a standard 9V battery mounted in the area above the display.



Resources for Further Information


Original text and images Copyright © John Wolff 2002-13.
Last Updated: 7 November 2013

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