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Calculators: Handheld: Detson E420
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Size (approx): | 90mm x 142mm x 30mm (max) (w,h,d) Weight 148g excluding batteries |
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Power: |
6V with 4 x AA size batteries. It accepts an adapter (6V DC, 300mW series 255A) through a socket on top side to the far right. A rear label states "Caution: the batteries supplied with this unit are not rechargeable. To avoid possible damage to unit, these batteries must be removed when using an AC adapter." | ||
| Case: | Constructed from a two piece smooth beige plastic case with a darker beige keyboard surround. A tilted but flat neutral plastic display filter has a rounded escutcheon moulded as part of the case. Below this is the brand name printed in black text, whilst the power switch is labelled in white text. The keys are squishy but positive in subtle colours. It has a handy brief instruction panel on the back. | ||
| Display: | 8 digit blue VFD with a ninth digit for negative, overflow and memory indicators | ||
| Features: | 4 function calculator with percentages, change sign, reciprocal, square root, register exchange and four function memory | ||
| Age: | 1976 | ||
| Manufacturer: | Detson, made in Japan, serial number 6D-101263 | ||
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Comments:
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How lovely, looks like something out of Blake's Seven - stunning. Very sound logic let down only by the lack of recovery. This is probably a re-branded Lloyd's calculator and one of a range of Detson calculators. |
| Components: | 1 x CPU: Texas TMS1071NL KBSL
7610 (week 10 of 1976), 28 pin staggered DIL, 0.6" width black plastic
with 1 x 9 digit VFD: single tube round face: Futaba 9-CT-08 6B (February 1976) 2 x transistors 3 x diodes 7 x capacitors 10 x resistors 2 x resistor arrays 1 x transformer: DCT-10B TDK Japan |
| Boards: | The keyboard assembly (E311-2 TMS1071 T-1 GK357-1 GICO Japan), sits loose on top of the main cpu board (L81T-C8) and is connected via 15 strong copper wires (only 13 of which look to be connected). |
| Construction: | Very difficult to open as it is held together by internal lugs only and the case is very stiff. I would not advise opening it as damage can easily result. The best was I found was to prize apart the sides by pushing in the rear section. When wedged open with some wooden coffee stirrers, you can then pop the bottom edge by again pushing n the rear section. |
| Logic comments: | The (CE) is used to clear last entry of a number and (C) to clear the whole calculator. |
| Overflow on number input is suppressed, typing in a ninth digit is ignored | |
| There is automatic constant on all functions | |
| An overflow error is flagged with the result and "º" in the far left (ninth) digit and is not recoverable | |
| Divide by zero results in zero and "º" in the far left (ninth) digit and is not recoverable | |
| Negative numbers are shown with a "-" to the immediate left of a number travelling into the far left (ninth) digit thereby allowing full eight digit negative numbers | |
| The change sign key will operate on mid entry of a number | |
| The EX register exchange reverses the order of the last register with the displayed number; i.e. (1)(0)(/)(2)(X-y)(=) gives "0.2" instead of five | |
| The percentage key in isolation just divides by 100 | |
| Memory store is indicated by an "r" in the far left (ninth) digit | |
| You can store an overflow in memory but can only recall it with (MR), (C) will then clear the memory and calculator | |
| No bugs found |
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With the front
removed you can see how the keyboard assembly sits on top of the battery
compartment and main cpu board. Most of the components are obscured
but you can see the two resistor arrays just below the display tube..
This format, with the GICO keyboard is very similar to Lloyd's/Lloytron models as well as ones from Decimo. |
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