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Calculators: Handheld: HTH 830D
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| Size (approx): |
73mm
x 117mm x 19mm (max) (w x h x d) |
| Power: | 1.5V DC using 1 x AA size batteries. It accepts an adapter/charger (1.5V DC, centre positive) through a socket on the top side to the far left. |
| Case: | Two piece black and off-white glossy plastic case with a pronounced rim around the edges. The top has a full-width black printed aluminium panel that sits in its own recess with the model name. The display filter is black and neutral flush plastic that is very slightly tilted. It lets in a little too much light, exposing the display too much. The keyboard surround is a recessed matching brushed aluminium panel, The concave keys are light touch, springy with a soft click and work well enough. |
| Display: | 8 digit blue VFD with a ninth digit for negative, memory and error indicators |
| Features: | Standard four functions with percentage, square root, pi, squares, reciprocal and change sign. |
| Age: | estimate 1977 |
| Manufacturer: | HTH Electronic manufactured by Detron Co., (I suspect in Korea) serial number 7110275. |
| Comments: | Small unusual model that is similar to the Silver Reed 80 and other Similar Calculators. Let down by the low contrast display filter. The original cover is soft black plastic with an open top and side half-moon cut-outs. The logic is average, let down by the lack of recovery, negative square roots and input overflow. |
| Components: | 1 x cpu: NEC D1801C R6933M, 28 pin
DIL, 0.6" width black plastic 1 x 9 digit VFD; single glass tube with round front face 2 x transistors 4 x diodes 5 x capacitors 2 x resistors 1 x transformer |
| Boards: | The main board (51202) sits on top of the keyboard assembly which is attached to the front with 10 screws. A 15-way ribbon cable joins them together. The transformer sits in its own cut-out to keep the board as slim as possible. |
| Construction: | Remove the single screw from the back and gently prize off the front starting at the bottom. There are two lugs either side. Eventually you will be able to hinge around the top area and then take the back to to the right. |
| Logic comments: | The (C) key is used to clear the whole calculator, there being no (CE) function |
| Input overflow is not suppressed inputting a ninth digit causes and overflow which is not recoverable | |
| Negative numbers are shown with a "-” in the immediate left hand digit travelling into the far left (ninth) digit, thereby allowing full eight digit negative numbers. | |
| There is automatic constant on all four functions | |
| Overflow shows the result and “C” (or “E” if negative) in the far left (ninth) digit and is not recoverable | |
| Divide by zero shows zero and “C” in the far left (ninth) digit and is not recoverable | |
| Negative square roots are allowed and result in a negative answer | |
| No other bugs found |
