View source for Sharp EL-8

{{Short description|Electronic calculator}}

{{Infobox calculator
| name           = Sharp EL-8
| image          = Sharp EL-8.JPG
| caption        = Sharp EL-8 of 1971
| manufacturer   = [[Sharp Corporation]]
| introduced     = 1970 or 1971
| predecessor    = [[Sharp QT-8D|QT-8D]], [[Sharp QT-8B|QT-8B]]
| cost           = JP¥84,800, US$345
| display_type   = 8-digit [[vacuum fluorescent display]]
| supply         = 6 [[Nickel-cadmium battery|Ni–Cd]] [[AA battery|AA batteries]] (450 mAh in total) or AC adapter
| power          = ~1W
| weight         = 0.72 kg
| dimensions     = 164 × 102 × 70 mm
}}

[[File:Sharp EL-8 The First Portable Electronic Calculator.jpg|thumb|right|Sharp EL-8 of December 1970]]
The '''Sharp EL-8''', also known as the '''ELSI-8''',<ref name="vintage"/> was one of the earliest mass-produced hand-held electronic [[calculator]]s<ref name="vintage"/> and the first hand-held calculator to be made by [[Sharp Corporation]]. Introduced around the start of 1971,{{#tag:ref |Some sources claim the EL-8's introduction was in January 1971,<ref name="oldcalc el8"/><ref name="dentaku"/> others claim it was in November 1970.<ref name="datamath"/><ref name="wolff"/> |group="note"}} it was based on Sharp's preceding [[Sharp QT-8D|QT-8D]] and [[Sharp QT-8B|QT-8B]] compact desktop calculators and used the same logic circuits, but it was redesigned to fit in a much smaller case.

Most electronic calculators before the EL-8 were intended for desktop use.<ref name="oldcalc el8"/> Sharp's predecessor to the EL-8, the battery-powered QT-8B, was just a portable version of a compact desk calculator.<ref name="vintage"/> The EL-8 was much smaller, small enough to be used in one's hand: {{convert|6.46|in|disp=flip|abbr=on}} long, {{convert|4.02|in|disp=flip|abbr=on}} wide, and {{convert|2.76|in|disp=flip|abbr=on}} thick, and weighing {{convert|1.59|lb|disp=flip|abbr=on}} with batteries.<ref name="electronics"/> Although it was still too bulky to easily fit in a pocket,<ref name="vintage"/> it was an important step toward the development of the pocket calculator.<ref name="oldcalc el8"/>
[[File:Sharp ELSI-8 commercial.jpg|left|thumb|Ad showing the calculator's original price.]]
The EL-8's original price in Japan was 84,800 [[Japanese yen]].<ref name="dentaku"/> The retail price in 1971 was {{Inflation|US|fmt=eq|orig=yes|cursign={{USD}}|345|1971|2021}}.<ref name="vintage"/><ref name="inflation"/>

==Operation and design==
The operation and performance of the EL-8 are identical to its predecessor calculators, the QT-8D and QT-8B, because its logic circuits use the same set of four [[Rockwell International|Rockwell]]-manufactured [[Large-scale integration|large-scale]] [[integrated circuit]]s.<ref name="vintage"/><ref name="oldcalc el8"/><ref name=Shirriff1220/> Likewise, its keyboard has the same layout, including the combined {{key press|×÷}} key,<ref name="vintage"/><ref name="oldcalc el8"/> and it also uses magnetic [[reed switch]]es.<ref name="classiccmp"/>

The display, like that of the QT-8D, is an 8-digit [[vacuum fluorescent display]] with nine individual tubes: eight digit tubes and a single extra tube for the minus sign and overflow indicator. As with the QT-8D, the tubes are Iseden "itron" tubes<ref group="note">"Iseden" is an abbreviation for the manufacturer's full name, {{nihongo3|"Ise Electronics Industry Stock Company"|伊勢電子工業株式会社|Ise Denshi Kōgyō Kabushiki Kaisha}}, known in English as Ise Electronics Corporation.</ref> with the same distinctive "handwritten" digit style and the same half-height "0". However, unlike the QT-8D, the EL-8 digit tubes only have [[Eight-segment display|eight segments to form digits]], and the EL-8's extra tube is positioned at the top right corner of the display instead of at its right end. A separate lamp serves as a power indicator.<ref name="vintage"/><ref name="oldcalc el8"/><ref name="classiccmp"/>
[[File:Sharp EL-8 Itron vacuum-fluorescent Display Tube.jpg|thumb|left|Itron DG10L Vacuum-Fluorescent Display Tube]]

Power is supplied by an integrated [[Rechargeable battery|rechargeable]] [[battery pack]] or by an external [[battery charger]], which also serves as an [[AC adapter]] to allow the calculator to operate from [[Mains electricity|AC power]].<ref name="oldcalc el8"/> The battery pack (model EL-84)<ref name="classiccmp"/> contains six [[Nickel-cadmium battery|nickel-cadmium]] [[AA battery|AA batteries]] connected in [[Series and parallel circuits|series]], giving a total [[voltage]] of {{val|7.2 |ul=volts}}<ref name="vintage"/> and, with the original batteries, a total capacity of {{val|450 |ul=mAh}}.<ref name="electronics"/> (Present-day nickel-cadmium AA batteries have much greater capacity.) Battery life with the original batteries is about three hours,<ref name="vintage"/> which gives an average power usage of about one [[watt]]. The battery charger (model EL-81) supplies power to the calculator's charging input at voltages of {{val|8.7 |and| 9.6 |ul=volts}};<ref name="classiccmp"/> the combined input power rating is about {{val|3.2|u=watts|ul=}}.<ref name="rechnerwiki"/>
[[File:Sharp NR-AA Re-chargeable Battery.jpg|thumb|right|Sharp NR-AA Rechargeable Battery]]

The EL-8's battery pack is much smaller than that of the QT-8B, and this was critical in reducing the EL-8's size and weight. However, these smaller batteries have much less capacity, and in order to maintain reasonable battery life, power usage had to be drastically cut. This was done by various improvements in the electronics, especially in the display. The QT-8B's display tubes are driven by discrete [[transistor]]s; to reduce the number of transistors needed, only one tube is lit at a time, and the circuitry cycles through the tubes in rapid sequence. The rapid switching from tube to tube requires load [[resistor]]s which absorb a lot of power. In the EL-8, the display tubes are driven by integrated circuits containing multiple transistors, and all of the tubes are kept lit constantly. No switching is required and no load resistors are needed, so much less power is used. Furthermore, because each tube in the QT-8B is only lit for a fraction of the time, the tubes need a high momentary brightness in order to get a reasonable average brightness, so they must be driven with a high voltage, requiring a separate high-voltage power supply. Since the EL-8 tubes are kept constantly lit, they don't have to be as bright, so the driving voltage can be lower and a separate high-voltage supply is not needed. In addition to the display improvements, the EL-8 also has a more efficient [[clock generator]] circuit for its logic than the QT-8B. Together, these changes reduced the EL-8's power usage to less than a third of that of the QT-8B.<ref name="electronics"/>

==Related models==
Sharp also produced a version of the EL-8 without batteries called the '''EL-8A'''. This was offered at a lower price, about {{Inflation|US|fmt=eq|orig=yes|cursign={{USD}}|300|1971|2021}}.<ref name="inflation"/> Since this version lacks batteries, it is somewhat lighter and requires an AC adapter for power. The power connector is also slightly different, having an extra contact.<ref name="datamath el8a"/>

In addition to its own EL-8 and EL-8A, Sharp also built [[OEM]] versions of the EL-8 for the Swedish office machine company [[Facit]] and its subsidiary [[AB Addo|Addo]], which sold them as the '''Facit 1111''' and the '''Addo-X 9364'''. These have the same internals as the EL-8, but the case and keycaps are different.<ref name="vintage"/><ref name="oldcalc facit"/>

== Notes ==
<references group="note"/>

== References ==
{{Reflist|
refs=
<ref name="vintage">{{Cite web |author=Nigel Tout |url=http://www.vintagecalculators.com/html/sharp_el-8.html |title=Sharp ''EL-8'', Facit ''1111'', & Addo-X ''9364'' |work=Vintage Calculators Web Museum |accessdate=October 7, 2010}}</ref>
<ref name="oldcalc el8">{{Cite web |author=Rick Bensene |url=http://www.oldcalculatormuseum.com/sharpel-8.html |title=Sharp EL-8 'Handheld' Electronic Calculator |work=The Old Calculator Web Museum |accessdate=October 8, 2010}}</ref>
<ref name="dentaku">{{Cite web |author=Shinichiro Osaki |url=http://www.dentaku-museum.com/calc/calc/1-sharp/2-elled/elled.html#el8 |title=シャープ EL シリーズ （ポケット蛍光管 タイプ）: EL-8 |language=Japanese |trans-title=Sharp EL series (pocket fluorescent-tube type): EL-8 |work=Dentaku Museum |accessdate=October 8, 2010}}<br>
"{{Nihongo|In January 1971, a small, portable electronic calculator was released....The price at that time was 84,800 yen.|1971年1月に発売された小型、携帯型電卓。...当時の価格 84,800円。|1971 nen 1 gatsu ni hatsubai sareta kogata, keitaigata dentaku....Touji no kakaku 84,800 en.}}"</ref>
<ref name="datamath">{{Cite web |author=Joerg Woerner |url=http://www.datamath.org/Related/Sharp/EL-8.htm |title=Sharp EL-8 |work=Datamath Calculator Museum |accessdate=October 8, 2010}}</ref>
<ref name="wolff">{{Cite web |author=John Wolff |url=http://www.johnwolff.id.au/calculators/Sharp/EL8-8M/EL8-8M.htm |title=Sharp EL-8 and EL-8M Portable Calculators |work=John Wolff's Web Museum |accessdate=July 30, 2014}}</ref>
<ref name="electronics">{{cite journal |date=February 1971 |title=How to cut a pocket calculator in half |journal=Electronics |volume=44 |page=120 |issn=0013-5070 |url=https://books.google.com/books?id=SbWzAAAAIAAJ&q=%22How+to+cut+a+pocket+calculator+in+half%22 |accessdate=October 7, 2010}}<br>
[http://www.vintagecalculators.com/html/sharp_el-8.html Nigel Tout's EL-8 page] includes an extended quote from this article.</ref>
<ref name="inflation">{{Cite web |url=http://www.bls.gov/data/inflation_calculator.htm |title=CPI Inflation Calculator |publisher=[[Bureau of Labor Statistics]] |accessdate=October 6, 2010}}</ref>
<ref name="classiccmp">{{Cite web |author=Alex Knight |url=http://www.classiccmp.org/calcmuseum/EarlySharp.htm |title=Early Sharp Calculators Internal Photographs |work=The Calculator Museum Web Page |accessdate=October 8, 2010}}</ref>
<ref name="rechnerwiki">{{Cite web |author=Fritz Gallwitz |url=http://www.schlepptops.de/wiki/index.php?title=Sharp_EL-8 |title=Sharp EL-8 |language=German |work=Rechnerwiki |accessdate=October 6, 2010}} (See photo of back panel.)</ref>
<ref name="datamath el8a">{{Cite web |author=Joerg Woerner |url=http://www.datamath.org/Related/Sharp/EL-8A.htm |title=Sharp EL-8A |work=Datamath Calculator Museum |accessdate=October 9, 2010}}</ref>
<ref name="oldcalc facit">{{Cite web |author=Rick Bensene |url=http://www.oldcalculatormuseum.com/facit.html |title=Facit 1111 'Handheld' Electronic Calculator |work=The Old Calculator Web Museum |accessdate=October 7, 2010}}</ref>
<ref name=Shirriff1220>{{cite web |first=Ken |last=Shirriff |title=Reverse-engineering the clock chip in the first MOS calculator |date=December 2020 |url=http://www.righto.com/2020/12/reverse-engineering-clock-chip-in-first.html}}</ref>
}}

== External links ==
* Two Sharp television ads for the EL-8 (called "ELSI-8" in the ads): [https://archive.org/details/sharp_calculator ad 1], [https://archive.org/details/sharp_calculator_2 ad 2]
* [http://www.curtamania.com/curta/database/brand/sharp/Sharp%20EL-8/index.html The Sharp EL-8 family]
*{{cite web |first=Ken |last=Shirriff |title=Reverse-engineering an early calculator chip with four-phase logic |date=December 2020 |url=http://www.righto.com/2020/12/reverse-engineering-early-calculator.html}}

{{Sharp Corporation}}

[[Category:Sharp Corporation calculators|EL-8]]
[[Category:Computer-related introductions in 1970]]