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If the memory contains any value other than 0, an M sign is appears on the right of the display. If the left switch is in the rightmost setting (∑), the memory automatically accumulates results obtained by pressing the += and -= keys. If the result can not be displayed with the specified decimal digits due to long integer part, the calculator automatically decreased the number of decimal places.
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To clear the error sign, press the C key. If the result overflows (if the integer part exceeds 12 digits), a small circle appears in the right of the display. The constant switch can be operated as with other calculators used arithmetic logic, so the first keyed number will be the constant for further multiplications or divisions. The display shows 30 (without decimal point), after pressing the ↔ the display changes to 26.730185. To switch to the second display and vice versa, press the ↔ key. The first display shows only the leftmost places, and the second shows the 8 lower significant digits. Up to 12 digits can be entered, of which 7 can be fractional.ĭisplaying results are unusual if the number exceeded the 8 digit capacity.
#What did the friden calculator series
The principle was simple, a frame holding a series of rods, with ten sliding beads on each. The numbers keyed in can be other format than the decimal setting, the calculator will automatically rounds the results if needed. The Abacus: Bean counters friend In the very beginning, of course was the abacus, a sort of hand operated mechanical calculator using beads on rods, first used by Sumerians and Egyptians around 2000 BC. To calculate without summarizing to memory, the left switch must be in the center position. Entering greater number than 7 will result in 7 decimal places. To set the decimal places, place the left switch to leftmost position (DS = Decimal Selection) and press the appropriate number key (0-7).
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All results obtained with += and -= key will be rounded to the specified decimal places. The important ICs were produced by Hitachi, the VFD tube is from Futaba, all internal components are japanese made.Īt power on, the machine calculates with 0 decimal places. It has unique calculating capabilities: the machine has an internal precision of 12 digits (of which 7 can be decimal), but the display capacity is only 8 digits and computes with fixed decimal point. Hitachi developed the KK 221B calculator in 1973, which was distributed under the name Singer-Friden 1200 too. Later, more arrangements were concluded with other, mostly japanese calculator manufacturers. So Hitachi’s products were sold in the US and Europe under the well-known Friden and Singer brands. The new management saw that they could not compete with japanese manufacturers in long term, so an arrangement between Singer and Hitachi was established to develop and distribute electronic calculators. Well-known sewing machine manufacturer, The Singer Corporation established in 1851, due to declining home sewing, they decided to enter new markets, so Singer purchased a calculator manufacturer, Friden Inc.