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Calculators: Handheld: Binatone (unknown name)
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| Size (approx): | 66mm x
125mm x 22mm (max) (w,h,d) Weight 98g excluding batteries. |
| Power: | 9.0V DC, 1 x PP3 size battery. Also accepts an adapter (undefined) through socket on the top side to the far right. The on/off switch is on the right hand side, in line with the brand name. The battery compartment has a black ribbon pull to aid battery removal - and it's needed. |
| Case: | Two piece gloss dark brown and white case sloped at a slight angle. The front is dominated by an oversized, wrap-over red plastic display filter. This filter has a black printed metallic sticker sitting in a recess with the brand name. A window on the display filter shows a bright enough image but with limited viewing angle. black plastic case with substantial brushed aluminium panels either side giving it a quality feel. The keys are short travel with a muffled click. |
| Display: | 8 digit red LED with individual bubble lens and a ninth digit for negative and error indication |
| Features: | Basic four function with percentages |
| Age: | 1975 |
| Manufacturer: | Undefined make, country of origin and no serial number. |
| Comments: | Sturdy and solid feeling calculator that is very attractive with its dominant red plastic top. I have had to restore this example considerably, so it might have had a model number printed on the display area. The logic is average with no recovery and two negative zero bugs. The original case is soft dark brown patterned plastic with Binatone embossed on the front. It has a carry strap to the side and a top flap with front popper closing. |
| Components: | 1 x IC: Unknown EA 7055 a 7523
(date code week 23 of 1975), 28 pin DIL, 0.6" width black ceramic with gold
pins 1 x 9 digit LED module, with bubble lenses: Antex SK-3-307 11 x transistors 1 x diode 4 x capacitors 18 x resistors 1 x choke |
| Boards: | The main cpu board (3024) is held in place by four plastic clips and is joined to the keyboard (7055) by nine flying wires. The main board has a wax coated piggy back board for the power supply components. |
| Construction: | Held together by internal lugs only and quite difficult top open as the sides are so stiff. If you must try, start at the side by gently pushing in the white section and travel along the bottom and next side. The red plastic filter will also separate this way. You can then remove the back, which you will discover has a large hole in it, masked by the instruction label. The plastic display filter has a linear lens for additional magnification of the display. |
| Logic comments: | (C) cancels the last number entered whilst a second press will clear the whole calculator |
| Input overflow is suppressed; inputting a ninth digit is ignored | |
| There is automatic constant on all four functions | |
| Negative numbers are represented by a "-" sign in the immediate left hand digit, travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers | |
| Overflow shows the result and "E." in the far left (ninth) digit and is not recoverable | |
| Divide by zero results in "E0.0000000" and is not recoverable | |
| It suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" then (+)(1)(=) to give "-0". | |
| It also suffers the divide to negative zero bug (oddly): key in (-)(1)(=)(¸)(1)(0)(=)(=)(=) etc until you get "-0.0000000" then (=) gives "-0." after a delay |
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The image left
shows the main cpu board in isolation. Notice the row of black
transistors at the top to drive the LED display digits.
Each digit on the display has its own magnifying bubble lens as the LEDs are rather small. You can also see the wax coated piggy-back board in the middle with the power components. I do not recognise the IC logo - can anyone help? (possibly Zilog?) |
