Calculating - Olivetti Summa Prima 20
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Olivetti 15 £sd
Olivetti 20 £sd
Olivetti Decimal
Plus
Victor
 
For an explanation of £sd money
see the Money page
 
 
 
 
 
5535240 is in good condition and has the later design, square keys.
 
 
 
5494106 has the older style round keys.
 
Olivetti
Model   Summa Prima 20
Maker   Olivetti
Origin   Italy
Date   1960s
Serial   5535240 and 5432893
 
A version equipped with additional 10 and 11 keys for sterling £sd currency or ½ for decimal money. A lever on the underside allows switching between £sd and decimal currencies. The ½ keys are only available in decimal mode.
 
A joystick selects subtraction, sub-total, total or number not to be included. The amount is entered, the joystick set if required and the handle pulled forward and released. The amount is printed on a paper roll, in black for individual amounts and in red for the total or sub-total, using a typewriter ribbon.
 
Care must be taken to enter a zero in front of single digit shillings amounts.
 
The original design dates from 1949 but the machine was made around 1960.
 
The machine is easily portable and mechanically reliable.
 
It seems that these machines were designed for the Australian and New Zealand markets. These countries withdrew the old halfpenny earlier than the UK and also made the change to decimal money before us. This would explain the lack of a ½ key in £sd mode.
 
     
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