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Calculators: Handheld: Imperial 91S
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Size (approx): | 73mm x
120mm x 20mm(max) (w,h,d) Weight 116g excluding batteries |
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Power: |
6V DC, 4 x AAA size batteries. It accepts an adapter (undefined but 2mm plug, centre negative) through socket on the bottom side to the far right. | ||
| Case: | Compact two-piece case made from black matt plastic. The front has a full size wrap over edge brushed aluminium panel. Recessed panel has a black printed paper label stating brand and model name. An inset and tilted green display filter give a bright display. Squishy keys work well enough with a subtle colour scheme. On/off switch doubles as a decimal point selector and has white printed labelling. | ||
| Display: | 8 digit green VFD, with a ninth digit for memory, minus and error indication. | ||
| Features: | Standard four functions, percentages, sign change, register exchange, pi, square root and four function memory. | ||
| Age: | 1976 | ||
| Manufacturer: | Imperial Business Equipment Ltd, Leicester, England. Serial No. 91S 69.276.314, made in Japan | ||
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Comments:
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Nice compact calculator with good range of functions. Logic very sound but somewhat quirky key labels (such as M out and the change sign key). From a British company more famous for its typewriters. Quite a high component count for such a late. This calculator is very similar in design to the Adler 81S of 1975 and quite like the Adler 81C. |
| Components: | 1 x cpu: Hitachi HD36265 6B 43
(Date code February 1976) 24-pin DIL, 0.6" width black plastic 1 x 9 digit flat faced glass tube VFD display 2 x transistor 8 x diodes 8 x capacitors 2 x resistor arrays 6 x resistors 1 x transformer: 04B Atlas |
| Boards: | The keyboard assembly sits on top of the main cpu board is is connected to it via 18 stiff wires. As this is soldered to the battery compartment connections as well as three short cables to the power socket. You must remove the socket to lift the whole assembly. |
| Construction: | Very gently push in the lugs of the lower section (one at each end and two on each side). The top will then lift off - not for the faint hearted. |
| Logic comments: | (CL) is used once to cancel the last number entered and (C) to clear the whole calculator. |
| There is automatic constant on all four functions | |
| Input overflow is suppressed, inputting a ninth digit is ignored | |
| Negative numbers are shown with a "-" in the far left (ninth) digit allowing eight-digit negative numbers | |
| The change sign key "(-)" can be used in mid-number entry but not before | |
| The on/off switch can be used to select [F] floating, two or three digit decimal points | |
| Divide by zero shows "E" in the far left (ninth) digit and is not recoverable | |
| Overflow shows the result with "E" in the left most (ninth) digit and is not recoverable | |
| Negative square roots show the result with an error status as above | |
| Pi is displayed in full eight digit notation when recalled whatever the decimal point selected | |
| Memory is indicated by the far left (ninth) showing "11" in the upper segments | |
| Overflow in memory is flagged but not recoverable and the memory holds the result shifted | |
| No bugs found |
