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Calculators: Handheld: Federal Student
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| Size (approx): |
75mm
x 130mm x 20mm
(w,h,d) Weight 110g excluding batteries |
| Power: | 3.0V, 2 x AA size batteries. It accepts an adapter (3V DC, 100mA, 3.5mm plug centre positive, 0.2W) through a socket on the top side to the far right. |
| Case: | Slab shaped calculator made from a two-piece black matt plastic case. The top and bottom end panels have a square ridged design. An oversized green plastic display filter is flat and flush and gives a clean bright image. Below the display is a ridged area with a small recess for a black printed metallic sticker bearing the brand and model name. A large wrap around brushed aluminium panel surrounds the keyboard and has black printed text for the higher functions and on /off switch label. The keys are short travel, squishy and in my example do not work very well. |
| Display: | 8 digit green VFD, with a ninth digit for minus, memory and error indication. |
| Features: | 4 function calculator with percentages, square roots, reciprocal, squares, change sign, pi and four-function memory |
| Age: | 1976 |
| Manufacturer: | Made in Japan, serial number 8540623 |
| Comments: | Cheap and cheerful calculator with some useful extra functions and a common body design. Odd ability to cope with numbers greater than eight digits like some of the early Sinclair models. Otherwise the logic is quite sound with no nasty bugs to catch you out. The original cover is think black plastic with open top and half-moon cut-outs. I know of at least two other models from Federal that used the same case (The Federal Compact and Federal Memory). |
| Components: | 1 x cpu; NEC µPD946C R62949, 28 pin DIL, 0.6" width 1 x 9 digit VFD; single round faced tube: Itron DP95A4, Japan 1 x transistor 4 x diodes 7 x capacitors 7 x resistors 2 x resistor arrays 1 x transformer |
| Boards: | The keyboard assembly (171-2Y-811R) sits on top of the main cpu board and is connected by 15-way ribbon cable. |
| Construction: | Very difficult to open as it is held together by internal lugs only and the sides are so stiff that you cannot pop them easily at all. Be warned damage may result so don't bother! |
| Logic comments: | The (CE) button is used to clear last entry of a number and the (C) clear the whole calculator. |
| Overflow on number input is not suppressed inputting a ninth digit results in an overflow but you can still carry on calculating | |
| An overflow shows the result with a “C” (or “E” if negative) in the far left (ninth) digit and is recoverable by dividing by a number. In fact you can still carry on calculations until eventually zero is shown. | |
| Divide by zero results in zero and a "C” in the far left (ninth) digit and is not recoverable | |
| There is automatic constant on all four functions | |
| Negative square roots are allowed and give a negative result | |
| Negative numbers are shown by a "-" in the far left (ninth) digit thereby allowing full eight digit negative numbers. | |
| Memory store is indicated by the decimal point of the far left (ninth) digit | |
| It is possible to store and manipulate an overflow in memory just as it is in the main register | |
| Higher functions are invoked with a two key sequence starting with (F) but there is no indication that this is selected except for a brief blanking of the display. | |
| The change sign function can be used in mid number entry |
