British Calculators

Home > British Calculators

Addo

Addo and Addo-X

 

Anthea Agrell has kindly provided the following information about Addo:

"My grandfather, Hugo Agrell, founded Addo AB in Malmö, Sweden in 1918. My father took it to the US in 1950. As far as I know the company in the UK, in Cirencester, was a subsidiary of the Swedish company where my uncle became the MD.

What I do know with certainty is that my grandmother received the ceremonial keys to the town of Cirencester - where the factory which manufactured the machines was located - as a token of their enthusiasm that jobs were being created. I also remember the name of the British agents as being Ian Bulmer and his brother. They were located in London. I believe they did a pretty good job since as late as 1990 Addo-X's were still in use !"

Addo are mainly known for their mechanical calculators. The full-keyboard machines have the name Addo and the 10-key machines have the name Addo-X (X from the Roman numeral for 10, maybe). However, they did have a few models of electronic calculators:

  • Addo Ten/3.
  • Addo-X 9354J was made in Japan and is similar to the Sharp QT-8D.
  • Addo-X 9364 was made in Japan and is similar to the Sharp EL-8.
  • Addo-X 9675, described below, was manufactured in Britain.

ADDO-X 9675

ADDO-X 9675

Addo-X 9675

Power source - AC.

Display is 10 digits, "Nixie"- type tubes.

4-functions, %, memory.

Main integrated circuits - Plessey 7-item chipset with MP931B, MP932B, MP933B, MP934B, MP935B, MP936B, MP937B.

275 x 197 x 97 mm (11.8" x 7.75" x 3.8").

Made in the United Kingdom.

Made about 1972.

Inside

Here the cover has been removed to reveal the "Nixie"-type tubes, with display-driver board behind under the power supply, and the main calculating board right underneath.

Main circuit board

The main calculating board with the 7-piece chip-set manufactured by Plessey.

This is one of the few calculator chip-sets manufactured by Plessey. It looks to be quite costly since it requires 7 ceramic encased integrated circuits. This calculator is believed to date from about 1972, and by then both Mostek and Texas Instruments were putting the electronics of a 4-function calculator in one small plastic encapsulated integrated circuit. So a chip-set like this would then not have been competitive.

Plessey was a major company in Britain involved in radio and television-chassis production, but is especially noted for being at the forefront of developments in electronic telephone exchanges throughout the 1960s, 1970s, and 1980s. It was taken over by GEC-Siemens in 1989.

Home
1) Mechanical Calculators
2) Desk Electronic Calculators
3) Hand-held Calculators
4) Non-Decimal Calculators
5) Calculator Companies
6) Calculator Photo Library
7) Collecting Calculators
8) British Calculators
9) Puzzle Corner
10) Calculator Time-line
11) Calculator Technology
12) To make a Pocket Calculator
13) Index to the Calculators
14) Calculator Resources
15) Frequently Asked Questions
16) Update Information
17) Vintage Calculator News
18) About this site
19) Search this Site

British calculators

Abatron
Addo
Advance Electronics
Ajax
Boots
Busicom / Broughtons
Calate
Commodore
Decimo
Exactus
Geller
Gemini
Gross
Guy's Calculating Machines
Hanimex
House of Fraser
Imperial & Royal
Invicta
Memory Devices
Muldivo
Okhai
Phytron
Plustronics
Prinztronic
Pye
Radofin, Taktile & Triton
Rockwell
Sinclair
Texet

Vintage Calculators

© Text & photographs copyright Nigel Tout  2000-2008 except where noted otherwise.