Sterling Currency Calculators
This is a low-cost, plastic, Abreviated-Keyboard, £sd adding machine. The mechanism is derived from that of the Comptometer, but with the keyboard and display reversed.
It has four £ decades, a single tens of shillings key, shillings, pence, and ¼ & ½ pence.
The machine illustrated above is displaying a total of £1,234 15s 11¼d.
To enter a number above 5 the operator has to press two keys in succession in that column which add up to the number required.
To enter 11 in the Pence column the operator has to press 3 keys !!, eg. (5)+(5)+(1).
203 mm x 233 mm x 70 mm. (8" x 9" x 3").
Introduced in the early 1950s it cost £18 12s 6d Sterling (about US$50).
Models advertised were:
Made in Denmark, distributed in UK. by Office Machinery Ltd. (Omal).
Looking underneath with the bottom cover removed shows that the calculator mechanism is cheaply made, largely from components stamped out of phenolic sheet.
Advertisement for the Contex from Office Magazine, 1955.