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Calculators: Handheld: Prinztronic Mini 7 (Dixons)
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Size (approx): | 55mm x 120mm x 12mm (max) (w,h,d) Weight 62g excluding batteries |
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Power: |
6V DC, 4 x AAA size batteries. Does not accept an adaptor. | ||
| Case: | Two-piece light and dark blue plastic case with light blue keyboard surround. Oversized red display filter. Very compact but slightly squeaky design. Buttons are clear see though with a positive click. As the buttons float lose the whole thing rattles like a box of matches. | ||
| Display: | 8 digit red bubble-lens LED (ninth digit on far left used for minus sign and error flags) | ||
| Features: | Standard functions, with square root, register exchange and percentages. | ||
| Age: | 1974 | ||
| Manufacturer: | Prinztronic, made in Hong Kong. Serial No. 463489 on battery compartment door. Also have 450777 | ||
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Comments:
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First striped down calculator achieving the price for the masses in the UK. Familiar design used for a number of variants. Original case is square shaped black plastic with open top. Lovely to watch all the numbers cycle as it takes a second to work out a square root. Very few components to keep costs to an absolute minimum. |
| Components: | 1 x CPU; Texas TMC0807NC 7439
(28 pin DIL) (week 39 of 1974) 1 x display driver; Nat Semi 510DS/DN 8864N (22 pin DIL) 1 x 9 digit bubble lens red LED display 2 x resistors 1 x capacitor 1 x transformer; Astec AA 2124 |
| Boards: | The keyboard board is not fixed to body so the whole assembly can be lifted out. The keyboard board is also the cpu board which is connected to the display board by an 18-way connector. The display board holds the display drive chip and one resistor. |
| Construction: | Gently push and twist a screwdriver on the right hand side looking from the rear. Inside the battery compartment you will just see a fixing lug. About 2cm from the top and the bottom there are others on this side. By the time these two are popped you can do the top and bottom lugs and finally the three on the other side. |
| Logic comments: | (CE) is used to cancel last entry (C) clears the whole calculator. |
| There is automatic constant on all four functions. | |
| Input overflow is suppressed, inputting a ninth digit is ignored | |
| Negative sign is shown in the ninth (far left) digit thereby allowing full eight digit negative numbers. | |
| You are allowed negative square roots. | |
| Divide by zero shows zero plus "u" in the far left ninth digit. It is recoverable using (CE) | |
| Overflow is shown by "u" in the far left digit ("o" if negative) and is recoverable using (CE) | |
| A power saving close down operates after 20 seconds - showing a minus sign in the ninth digit | |
| The (RE) key is used as a register exchange function - to swap the last number entered with the first - useful for reciprocals | |
| The (D) is used as a Display recover key to reset the power save mode |
