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{{Short description|Early microcomputer company}}

{{Infobox company
| name=Ohio Scientific, Inc.
| former_name={{ubl|Ohio Scientific Instruments, Inc. (1975–1979)|M/A-COM Office Systems, Inc. (1981–1983)}}
| logo=Ohio Scientific wordmark.svg
| founded={{start date and age|1975}} in [[Hiram, Ohio]]
| founders={{ubl|Michael Cheiky|Charity Cheiky|Dale Dreisbach}}
| hq_location=[[Aurora, Ohio]], United States
| defunct={{end date and age|1983|12}}
| fate=Acquired by [[M/A-COM]] in 1980; later sold to Kendata in early 1983, then Isotron, Inc. ({{ill|AB Fannyudde|sv}}), in late 1983, then [[Dataindustrier AB]] in 1986
| parent={{ubl|M/A-COM (1981–1983)|Kendata (1983)|Isotron, Inc. (1983–1986)}}
| products=See [[#Products|§ Products]]
| industry=Computer
| type=Private
| num_employees=300 (1980, peak)
}}

'''Ohio Scientific, Inc.''' ('''OSI''', originally '''Ohio Scientific Instruments, Inc.'''), was a privately owned American computer company based in Ohio that built and marketed computer systems, expansions, and software from 1975 to 1986. Their best-known products were the Challenger series of [[microcomputer]]s and Superboard [[single-board computer]]s. The company was the first to market microcomputers with [[hard disk drive]]s in 1977.

The company was incorporated as Ohio Scientific Instruments in [[Hiram, Ohio]], by husband and wife Mike and Charity Cheiky and business associate Dale A. Dreisbach in 1975. Originally a maker of electronic teaching aids, the company leaned quickly into microcomputer production, after their original educational products failed in the marketplace while their computer-oriented products sparked high interest in the hobbyist community. The company moved to [[Aurora, Ohio]], occupying a 72,000-square-foot factory. The company reached the $1&nbsp;million revenue mark in 1976; by the end of 1980, the company generated $18&nbsp;million in revenue. Ohio Scientific's manufacturing presence likewise expanded into greater Ohio as well as California and Puerto Rico.

In 1980, the company was acquired by telecommunications conglomerate [[M/A-COM]] of [[Burlington, Massachusetts]], for $5&nbsp;million. M/A-COM soon consolidated the company's product lines, in order to focus their new subsidiary on manufacturing business systems. During their tenure under M/A-COM, Ohio Scientific was renamed '''M/A-COM Office Systems'''. M/A-COM struggled financially themselves and sold the division in 1983 to Kendata Inc. of [[Trumbull, Connecticut]], who immediately renamed it back to Ohio Scientific. Kendata, previously only a corporate reseller of computer systems, failed to maintain Ohio Scientific's manufacturing lines and subsequently sold the division to AB Fannyudde of Sweden. The flagship Aurora factory, by then only employing 16 people, was finally shut down in October 1983.

== Beginnings (1975–1976) ==
[[File:Mike and Charity Cheiky of Ohio Scientific.jpeg|thumb|Co-founders Mike and Charity Cheiky pictured in 1978 with a Challenger 2P]]

Ohio Scientific was founded in [[Hiram, Ohio]], in 1975 by Dale A. Dreisbach ({{circa}} 1909&nbsp;– June 16, 1987<ref>{{cite journal | last=Staff writer | date=June 21, 1987 | url=https://www.newspapers.com/clip/119072295/obituary-for-dale-a-dreisbach/ | title=Dale A. Dreisbach, Ph.D. | journal=The Akron Beacon Journal | page=70 | via=Newspapers.com}}</ref>) and husband and wife Michael "Mike" Cheiky (January 1, 1952&nbsp;– December 7, 2017<ref>{{cite web | date=n.d. | url=https://www.legacy.com/obituaries/name/michael-cheiky-obituary?pid=187501067 | title=Michael Cheiky Obituary | publisher=Legacy.com | archiveurl=https://web.archive.org/web/20230219084354/https://www.legacy.com/obituaries/name/michael-cheiky-obituary?pid=187501067 | archivedate=February 19, 2023}}</ref>) and Charity Cheiky (born {{circa}} 1954).<ref name=Geiger1978 /> Mike Cheiky had worked at the [[Solon, Ohio|Solon]]-based [[Ohio Nuclear|Ohio Nuclear Company]]—makers of medical equipment—as director of engineering, while Charity Cheiky had been employed at [[Western Reserve Academy]] as a professor of math and computer science.<ref name=Geiger1978 /><ref>{{cite journal | last=Geiger | first=Peter | date=June 20, 1982 | url=https://www.newspapers.com/clip/119058595/high-tech-could-play-key-role-for/ | title='High tech' could play key role for area, but competition is stiff | journal=The Akron Beacon Journal | page=B3, [https://www.newspapers.com/clip/119058662/high-tech-could-play-key-role-for/ B8] | via=Newspapers.com}}</ref>{{rp|B3}} Dreisbach meanwhile was a chairman and [[professor emeritus]] of [[Hiram College]]'s chemistry department;<ref name=Geiger1978 /> the Cheikys had met at Hiram College.<ref name=Reitz>{{cite journal | last=Reitz | first=Tom | date=February 12, 1981 | url=https://www.newspapers.com/clip/119059767/former-springville-girl-joins-ranks-of/ | title=Former Springville Girl Joins Ranks of New Millionaires | journal=Springville Journal | page=1 | via=Newspapers.com}}</ref> The three founded Ohio Scientific with between $5,000 and $25,000 of start-up capital.<ref name=Price-Root>{{cite journal | last=Price-Root | first=Susan | date=August 17, 1981 | url=https://www.newspapers.com/clip/119058194/entrepreneurs-just-dont-see-risk/ | title=Entrepreneurs just don't see risk | journal=Dayton Daily News | page=10 | via=Newspapers.com}}</ref><ref name=Valigra>{{cite journal | last=Valigra | first=L. | date=January 1982 | url=https://archive.org/details/bitsavers_MiniMicroS_206762522/page/63/ | title=OSI transforms under new president | journal=Mini-Micro Systems | publisher=Cahners Publishing | volume=XV | issue=1 | pages=63–64 | via=Gale}}</ref>{{rp|63}}<ref name=Jakobson>{{cite journal | last=Jakobson | first=Cathryn | date=September 1984 | url=https://archive.org/details/sim_working-woman_1984-09_9_9/page/n205/ | title=Five Good Reasons to Sell Your Business—And How to Make the Most of It When You Do | journal=Working Woman | publisher=Working Mother Media | volume=9 | issue=9 | pages=194–206 | via=the Internet Archive}}</ref>{{rp|196}}

The company was originally outfitted from the Cheiky's garage and was dedicated to the production of electronic teaching aids.<ref name=Geiger1978 /> The company's original name—Ohio Scientific Instruments, Inc.—reflected this initial purpose.<ref name="Cleveland">{{cite journal | last=Wickham | first=Bob | date=March 16, 1981 | url=https://books.google.com/books?id=iD4EAAAAMBAJ&pg=PT23 | title=Making Micros in Cleveland | journal=InfoWorld | publisher=IDG Publications | volume=3 | issue=5 | page=24 | via=Google Books}}</ref> The first products the company released included a [[calculator]] that also taught the basics of [[statistics]] and a single-board [[microcomputer]].<ref name=money>{{cite journal | last=Runde | first=Robert | date=January 1981 | url=https://www.newspapers.com/clip/119059835/they-became-millionaires-through-their/ | title=Seven Who've Made It Big | journal=Money | publisher=Time Inc. | volume=10 | issue=1 | page=40 | via=Newspapers.com}}</ref><ref name="Cleveland" /> The latter, called the Microcomputer Trainer Board and incorporating a [[MOS Technology 6502]] [[microprocessor]],<ref name=timetable>{{cite book | last=Spencer | first=Donald D. | date=1999 | url=https://archive.org/details/timetableofcompu00spen/page/94/ | title=The Timetable of Computers: A Chronology of the Most Important People and Events in the History of Computers | publisher=Camelot Publishing | page=94 | isbn=9780892183463 | via=the Internet Archive}}</ref> was designed by Mike, inspired by his experience with microprocessor-based [[minicomputer]]s at his Ohio Nuclear job.<ref name=Geiger1978 />

Most of the educational products sold poorly due to the lack of a strong local market for them, according to Mike.<ref name=Geiger1978 /> However, the Microcomputer Trainer Board saw high demand.<ref name="Cleveland" /> Most fruitful was a quarter-page advertisement in an early issue of ''[[Byte (magazine)|Byte]]''—a magazine for microcomputer hobbyists—with orders for the board totaling $100,000 within a few months.<ref name="Cleveland" /> The board generated $20,000 in sales for the trio,<ref name="AutoKV-4">{{cite book | last=Vesper | first=Karl H. | date=1993 | url=https://archive.org/details/newventuremechan0000vesp/page/57/ | title=New Venture Mechanics | publisher=Prentice Hall | isbn=0136207901 | via=the Internet Archive}}</ref> much more than they had originally anticipated.<ref name=Geiger1978>{{cite journal | last=Geiger | first=Peter | date=July 23, 1978 | url=https://www.newspapers.com/clip/119057449/new-vistas-open-up-in-little-computers/ | title=New vistas open up in little computers | journal=The Akron Beacon Journal | page=H-6 | via=Newspapers.com}}</ref> To keep up with growth, Cheikys moved the company to a 700-square-foot storefront in [[Hiram, Ohio]], last occupied by a barbershop and right next to a pizza parlor.<ref name="Geiger1978" /><ref name="Cleveland" />

== Growth (1976–1980) ==
With the release of their microcomputer systems and hardware in the mid-1970s, Charity Cheiky became the first woman at the helm of a personal computer manufacturer.<ref>{{cite book | last=Perry | first=Robert L. | date=1980 | url=https://archive.org/details/tibook_owning-your-home-computer/page/n99/ | title=Owning Your Home Computer | publisher=Everest House | page=99 | isbn=0896960935 | via=the Internet Archive}}</ref> In June 1976, Ohio Scientific had logged their first $1&nbsp;million in revenue. In late January 1978, the company moved from Hiram to [[Aurora, Ohio]], occupying a 72,000-square-foot factory formerly occupied by Custom Beverage. By that point, the company had employed 35. Within six months, the number of employees had reached 100. Cash flow increased in tandem: between 1977 and 1978, the company grossed $10&nbsp;million,<REF name="Geiger1978"/> and between 1978 and 1980, it logged sales of $20&nbsp;million.<ref name=holding>{{cite journal | last=Gibson | first=G. Thomas | date=May 1983 | url= | title=Holding onto Equity | journal=Venture | publisher=VenPub Inc. | page=62}} Quoted in {{cite book | last=Vesper | first=Karl H. | date=1993 | url=https://archive.org/details/newventuremechan0000vesp/page/188/ | title=New Venture Mechanics | publisher=Prentice Hall | isbn=0136207901 | via=the Internet Archive}}</ref> In 1980, Ohio Scientific generated $18&nbsp;million in revenues<ref name=Valigra />{{rp|63}}— $14.8&nbsp;million between January and October 1980 and $3.2&nbsp;million to the end of the year.<ref name=Valigra />{{rp|63}}<ref name=acquisition />

The Cheikys meanwhile felt that Ohio Scientific was growing too fast for them to adequately manage.<ref name=Reitz /> [[Stan Veit]], a business partner of Ohio Scientific as well as the founder of the first computer store in [[New York City]], called the company poorly organized and hard to contact. In his words, the company was "undercapitalized and very slow to deliver ordered equipment. This lost them a lot of the business they could have obtained because of their technical ability".<ref name=Veit1993>{{cite book | last=Veit | first=Stan | author-link=Stan Veit | date=1993 | url=https://archive.org/details/stan-veits-history-of-the-personal-computer/page/130/ | title=History of the Personal Computer | publisher=WorldComm | isbn=1566640237 | via=the Internet Archive}}</ref>{{rp|130}} In order to appease chagrined dealers who complained of long development times for the company's software, Ohio Scientific initiated a cooperative centralized software dealership program to spur the development of business applications for their computers in late 1978.<ref name=Veit1993 />{{rp|129}} In 1980, the company opened up two facilities in [[Cleveland]]: the first, a manufacturing plant early in the year; and the second, a 15,000-square-foot salesman training center opened in fall 1980.<ref>{{cite journal | last=Prince | first=Suzan D. | date=April 1981 | url=https://archive.org/details/sim_savvy-woman_1981-04_2_4/page/n23/ | title=Marketing Microcomputers | journal=Savvy | publisher=Family Media | volume=2 | issue=4 | pages=22–26 | via=the Internet Archive}}</ref> Ohio Scientific additionally opened a [[printed circuit board]] manufacturing plant in [[Puerto Rico]] around the time of their expansion into Cleveland,<ref name=Jakobson />{{rp|196}}<ref name="Cleveland" /> incorporating Ohio Scientific of Puerto Rico, Inc., in the process.<ref name=sign/> In November 1980, the company acquired the [[hard drive]] manufacturing division of [[Okidata]] in [[Goleta, California]], which manufactured the company's C-D74 drives that were used with their Challenger series of microcomputers.<ref name=Geffen>{{cite journal | last=Geffen | first=Paul | date=March 1981 | url=https://archive.org/details/Micro_NO._34_1981-03_Micro_Ink_US/page/n47/ | title=Challenges | journal=Micro | publisher=Micro Ink | issue=34 | page=46 | via=the Internet Archive}}</ref> After acquiring the division, Ohio Scientific folded it into their wholly owned Ohio Scientific Memory Products division.<ref>{{cite journal | last=Staff writer | date=December 15, 1980 | url=https://books.google.com/books?id=TTlCyc87XS8C&pg=RA1-PA62 | title=Okidata Winchester Line Sold to Ohio Scientific Memory | journal=Computerworld | publisher=CW Communications | volume=14 | issue=51 | page=62 | via=Google Books}}</ref><ref name=sign>{{cite journal|title=Ohio Scientific, M/A-COM Sign|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=December 8, 1980|volume=14|issue=50|page=64|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1980-12-08_14_50/page/64/}}</ref> By 1980, Ohio Scientific had 300 employees overall.<ref name=Jakobson />{{rp|196}}

== Sale (1980–1983) ==
Despite the software dealership initiative and the growing backbone of their manufacturing prowess, Ohio Scientific was never fully able to shake off their problems with software delivery.<ref>{{cite journal | last=Geiger | first=Peter | date=November 12, 1984 | url=https://www.newspapers.com/clip/119059143/a-victim-of-cabbage-patch-mania/ | title=A victim of Cabbage Patch mania | journal=The Akron Beacon Journal | page=B9 | via=Newspapers.com}}</ref> Still wanting an out, the Cheikys contacted a business friend, who got them in contact with [[M/A-COM]], a telecommunications conglomerate based in [[Burlington, Massachusetts]].<ref name=Jakobson />{{rp|196}} After discussion, M/A-COM agreed to acquire Ohio Scientific, publicly announcing their intent to purchase the company in November 1980. M/A-COM had recently absorbed [[Linkabit]], a technology company of [[San Diego, California]], in 1979. The terms of Ohio Scientific's sale were initially undisclosed,<ref name=acquisition>{{cite journal | last=Staff writer | date=November 22, 1980 | url=https://www.proquest.com/docview/294015152/ | title=M/A-Com Acquisition | journal=Boston Globe | page=1 | via=ProQuest}}</ref> later revealed to be $5&nbsp;million in cash. The Cheikys pocketed $3&nbsp;million, while Dreisbach received the rest.<ref name=money /> The acquisition was finalized in mid-December, underwritten by [[McDonald & Co.]] of [[Cleveland]].<ref>{{cite journal | date=December 16, 1980 | url=https://www.newspapers.com/clip/119058035/ohio-scientific-inc-aurora-ohio/ | title=Ohio Scientific, Inc. (Aurora, Ohio) has been acquired by M/A-Com, Inc. | journal=The Journal Herald | page=7 | via=Newspapers.com}}</ref> M/A-COM's decision to acquire a computer systems company surprised some in the telecommunications industry, but [[Irwin M. Jacobs]], president of M/A-COM, stated it was contingent with their push to supply offices with complete and comprehensive communications systems.<ref name=acquisition />

M/A-COM acquired all of Ohio Scientific's facilities, including those in Ohio, California, and Puerto Rico.<ref name=sign/> The Cheikys were briefly assigned advisor status in the company, but they were demoted, according to Charity, because M/A-COM disagreed with their guidance.<ref name=Jakobson />{{rp|196}} Instead, Harvey P. White replaced them as head of the subsidiary in December 1980. White left Ohio Scientific to helm M/A-COM's Linkabit subsidiary in July 1981.<ref name=changes>{{cite journal | last=Badgett | first=Tom | date=July 20, 1981 | url=https://books.google.com/books?id=tT0EAAAAMBAJ&pg=PA4 | title=Changes at Ohio Scientific | journal=InfoWorld | publisher=CW Communications | volume=3 | issue=14 | page=4 | via=Google Books}}</ref> Doug Hajjar was named as interim president before being replaced by William Chalmers later in the month. Chalmers beat out Chuck Kempton, a newly appointed marketing vice-president poached from [[Wang Laboratories]], for the position.<ref name=changes /><ref name=Wise>{{cite journal | last=Wise | first=Deborah | date=December 7, 1981 | url=https://books.google.com/books?id=gT0EAAAAMBAJ&pg=PA12 | title=New name, new address, new strategy planned for OSI | journal=InfoWorld | publisher=IDG Publications | volume=3 | issue=29 | page=12 | via=ProQuest}}</ref>

{{quote box|quote=The not-so-smooth acquisition of OSI has, within a year, virtually transformed the company, through M/A-COM resources, from a shoe-string, technical-product operation offering little documentation and support, into a $500-million company focusing on full solutions for users.|author=''[[Mini-Micro Systems]]'', January 1982<ref name=Valigra />{{rp|63}}|width=20%}}
Under ownership of M/A-COM in 1981, Ohio Scientific saw a drastic transformation in culture and corporate operations. While the company still operated as a subsidiary from its original headquarters in Aurora, the employees there soon became relegated to the status of a "support engineering group".<ref name=Valigra />{{rp|63}} The bulk of the subsidiary's research and development meanwhile was relocated to Burlington in early 1982.<ref name=Wise /><ref name=Valigra />{{rp|63}} A second research facility was also opened up in California—with Mike Cheiky named head of this—while Chalmers relocated from Aurora to Burlington.<ref name=Wise /> In December 1981, the subsidiary changed its name to M/A-COM Office Systems, Inc., reflecting these changes.<ref name=Wise /><ref name=Valigra />{{rp|63}} Chalmers explained in 1982: "This is not an Ohio or a scientific company any more".<ref name=Valigra />{{rp|63}} Massive consolidation of Ohio Scientific's 110 hardware and software products also occurred in 1982. The division was down to seven unique business systems that year (with optional configurations for each).<ref name=consolidates>{{cite journal | last=Valigra | first=L. | date=January 1982 | url=https://archive.org/details/bitsavers_MiniMicroS_206762522/page/63/ | title=OSI Consolidates Product Lines | journal=Mini-Micro Systems | publisher=Cahners Publishing | volume=XV | issue=1 | page=63 | via=Gale}}</ref> Further computer systems would be based on the [[Intel 8088]] processor and were slated to be installed with [[CP/M-86]].<ref name=Valigra />{{rp|64}}

== Demise (1983) ==
In August 1982, M/A-COM announced their intention to divest M/A-COM Office Systems by the end of the year. Spokespersons for the parent company cited M/A-COM's decision to refocus on high-speed digital communications, as well as higher-than-expect costs of developing hardware and software for general-purpose computer systems. M/A-COM was additionally suffering from large losses in the year to that point.<ref name=Rosenberg />

In February 1983, Kendata Inc. of [[Trumbull, Connecticut]], was named as M/A-COM Office Systems' buyer.<ref name=kendata>{{cite journal | last=Staff writer | date=February 1983 | url=https://archive.org/details/bitsavers_miniMicroS_195306134/page/60/ | title=In transition | journal=Mini-Micro Systems | publisher=Cahners Publishing | volume=XVI | issue=2 | page=60 | via=the Internet Archive}}</ref> A corporate reseller of [[Victor Technology|Victor]] computers,<ref name=dashed>{{cite journal | last=Staff writer | date=October 5, 1983 | url=https://www.newspapers.com/clip/119058967/high-tech-hopes-dashed-in-aurora/ | title=High-tech hopes dashed in Aurora | journal=Dayton Daily News | page=50 | via=Newspapers.com}}</ref> Kendata was one of two companies in talks with M/A-COM to acquire the division in 1982.<ref name=Rosenberg>{{cite journal | last=Rosenberg | first=Rosan | date=August 5, 1982 | url=https://www.proquest.com/docview/294252498/ | title=M/A-Com Plans to Sell Office Systems Division | journal=Boston Globe | page=1 | via=ProQuest}}</ref> The first order of business for Kendata was restoring the subsidiary's name back to Ohio Scientific, in order to take advantage of its existing brand presence.<ref name=kendata /> Kendata soon found themselves struggling to manage Ohio Scientific due a lack of technical and manufacturing prowess, however,<ref name=fierce />{{rp|D10}} as well as dealing with stiff competition from [[IBM]] and [[Tandy Corporation]].<ref name=fierce>{{cite journal | last=Byard | first=Katie | date=October 4, 1983 | url=https://www.newspapers.com/clip/119058909/competition-too-fierce-for-auroras/ | title=Competition too fierce for Aurora's OSI | journal=The Akron Beacon Journal | page=D7, [https://www.newspapers.com/clip/119058945/competition-too-fierce-for-auroras/ D10] | via=Newspapers.com}}</ref>{{rp|D7}} On October 3, 1983,<ref>{{cite journal | last=Staff writer | date=October 3, 1983 | url=https://www.newspapers.com/clip/119058815/microcomputer-plant-closes/ | title=Microcomputer plant closes | journal=Springfield News-Sun | page=18 | via=Newspapers.com}}</ref> Ohio Scientific's Aurora's factory was shut down, and the inventory liquidated, after Kendata had foreclosed on the property.<ref name=fierce />{{rp|D7}} The factory's 16 remaining employees were simultaneously let go.<ref>{{cite journal | last=Staff writer | date=October 3, 1983 | url=https://www.newspapers.com/clip/119058780/ohio-scientific-plant-in-aurora-is/ | title=Ohio Scientific plant in Aurora is closed | journal=The Akron Beacon Journal | page=B6 | via=Newspapers.com}}</ref> Locals lamented the closure of Ohio Scientific as the end of the high-tech industry for Aurora.<ref name=dashed />

Kendata sold the remaining assets of Ohio Scientific to {{ill|AB Fannyudde|sv}} of [[Sweden]] in December 1983. The latter absorbed Ohio Scientific under their Isotron, Inc., subsidiary.<ref>{{cite journal | last=Staff writer | date=December 16, 1983 | url=https://link.gale.com/apps/doc/A448762436/GPS?sid=wikipedia | title=Business Briefs | journal=UPI Archive: Financial | publisher=United Press International | via=Gale}}</ref> Ohio Scientific continued as a second-order subsidiary under Isotron until 1986, when [[Dataindustrier AB|Dataindustrier AB (DIAB)]] acquired Isotron from Fannyudde in 1986.<ref>{{cite web | last=Rawsthorn | first=Alice | date=April 28, 2014 | url=https://www.designcurial.com/news/richard-hamilton-and-design-4253773 | title=Richard Hamilton and Design | work=DesignCurial | publisher=Media International Limited | archiveurl=https://web.archive.org/web/20220910071241/https://www.designcurial.com/news/richard-hamilton-and-design-4253773 | archivedate=September 10, 2022}}</ref>

== Products ==
===Model 300 Computer Trainer Board (1976)===
Ohio Scientific are best remembered for their Superboard and Challenger lines, single-board and fully encased microcomputer systems respectively.<ref>{{cite journal | last=Thomas | first=Martyn | date=December 1980 | url=https://worldradiohistory.com/UK/Practical-Computing/80s/Practical-Computing-1980-12-S-OCR.pdf#page=118 | title=Book Review&nbsp;– ''The First Book of Ohio Scientific: Volume 1'' | journal=Practical Computing | publisher=IPC Electrical-Electronic Press | volume=3 | issue=12 | page=118 | via=World Radio History}}</ref> The first Superboards were first announced in the December 1975 issue ''Byte''.<ref>{{cite journal | last=((Ohio Scientific Instruments, Inc.)) | date=December 1975 | type=Advertisement | url=https://archive.org/details/byte-magazine-1975-12/page/n103/ | title=The 6000 Series Computer Family | journal=Byte | publisher=McGraw-Hill | issue=4 | page=102 | via=the Internet Archive}}</ref> Announced later,<ref>{{cite journal | last=((Ohio Scientific Instruments, Inc.)) | date=February 1976 | url=https://archive.org/details/sim_byte_1976-02_1_6/page/73/ | title=OSI Model 300 Computer Trainer | type=Advertisement | journal=Byte | publisher=McGraw-Hill | volume=1 | issue=6 | page=73 | via=the Internet Archive}}</ref> but probably preceding the first Superboards in production, was the Model 300 Computer Trainer Board,<ref name=timetable /> which features an MOS Technology 6502 microprocessor and 128&nbsp;Bytes of [[RAM]]. The board is {{convert|8|by|10|in|cm}} and requires an external 5&nbsp;V&nbsp;DC, 500&nbsp;mA power source.<ref name=model300>{{cite journal|title=Product Description: OSI|last=Baker|first=Robert|journal=Byte|publisher=McGraw-Hill|date=January 1977|volume=2|issue=1|pages=94–95|via=the Internet Archive|url=https://archive.org/details/sim_byte_1977-01_2_1/page/94/}}</ref>{{rp|94}} In a design scheme similar to a number of trainer boards of its contemporary, a number of slide switches on the bottom of the board connect directly to the MOS 6502's data, read–write, and address select pins, allowing the microprocessor to be halted and the RAM loaded with [[machine code]] instructions. A row of [[LED]]s connected in series with each line of the 6502's bus acts as a visual representation of the state of the processor.<ref>{{cite book | last=Amatneek | first=Karl V.| author2=Carroll R. Williams | date=1977 | url=https://books.google.com/books?id=9tYvAQAAIAAJ&q=%22ohio+scientific%22+%22computer+trainer%22+%22switches%22+%22data%22+%22address%22 | title=Proceedings UPIEEE-77 | publisher=Institute of Electrical and Electronics Engineers | page=109 | via=Google Books}}</ref> Ohio Scientific fully assembled each Computer Trainer Board, which came shipped with a manual; optional was a power supply and hardware and programming monographs.<ref>{{cite journal | last=Staff writer | date=November 1976 | url=https://archive.org/details/CreativeComputingV02n06NovDec1976/page/n19/ | title=Computer Trainer | journal=Creative Computing | volume=2 | issue=6 | page=18 | via=the Internet Archive}}</ref>

===Model 400 Superboard (1976)===
In September 1976, the company announced the Model 400 Superboard, a DIY [[Kit (of components)|kit]] which in fully assembled form runs either the [[MOS 6502]], the MOS 6501, or the [[Motorola 6800]] microprocessors. The Model 400 Superboard has a 48-line-wide [[Bus (computing)|bus]] at its edge, allowing it to be slotted into a [[backplane]] and take advantage of a number of expansion and peripheral boards,<ref name=model300 />{{rp|94}} including the Model 420 memory expansion board,<ref name=osi400 /> the Model 430 Super [[I/O]] board,<ref name=model300 />{{rp|95}} and the Model 440 Super Video graphics board.<ref name=osi400>{{cite journal | last=Staff writer | date=September 1976 | url=https://archive.org/details/sim_byte_1976-09_1_13/page/73/ | title=OSI 400 System | journal=Byte | publisher=McGraw-Hill | volume=1 | issue=13 | page=74 | via=the Internet Archive}}</ref><ref>{{cite journal|title=A New Graphics Option for OSI|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=November 1976|volume=1|issue=15|page=142|via=the Internet Archive|url=https://archive.org/details/sim_byte_1976-11_1_15/page/n143/}}</ref> The Model 400 can be outfit with up to 1&nbsp;kB of RAM, 512&nbsp;Bytes of [[programmable ROM|ROM]], an [[Asynchronous Communications Interface Adapter|ACIA]] chip for implementing [[RS-232]] or [[4–20 mA loop]] interfaces for serial communication, and a peripheral device adapter with 16 I/O lines.<ref name=model300 />{{rp|94}} It was built from [[G-10 (material)|G-10 fiberglass laminate]] and measures {{convert|8|by|10|in|cm}}. The 430 Super I/O board provides two 8-bit [[Digital-to-analog converter|DAC]]s, one 8-bit [[Analog-to-digital converter|ADC]], an 8-bit parallel port, and a number of serial interfaces for [[Computer terminal|terminal]] and [[teletype]] interaction and data storage, including [[Baudot code|Baudot]], [[ASCII]], [[Frequency-shift keying|FSK]], and [[Kansas City standard]]. Ohio Scientific offered both units on a rental basis in 1977, as part of their "315 plan", wherein users were given the Model 300 Trainer for two months, then are given the Model 400, 430, 440 boards, a keyboard, a data cassette interface, and documentation, once the Model 300 was returned.<ref name=model300 />{{rp|95}}

In August 1977, Ohio Scientific released the OSI 460Z. This was a multiprocessor expansion board kit for the Model 400 Superboard that greatly expands its software library by supporting several different kinds of microprocessors, including the [[Intersil 6100]] (a microprocessor-based implementation of [[Digital Equipment Corporation|DEC]]'s [[PDP-8]] minicomputer) and the [[Zilog Z80]] (which is software-compatible with the [[Intel 8080]] by design). The 460Z supports only Model 400s running the 6502 but allows the latter to fully control the 460Z, including accessing each line of the 6100 and Z80 and setting those processors in either single-stepping mode or full-speed operation. The Model 400 with the Model 460Z can execute code for multiple architectures by interrupts triggered for the 6502 to relinquish control to the secondary processors, and vice versa. The 6502 can execute code for itself while the other processors are busy, allowing for true [[multiprocessing]]. With the 460Z installed on bus, the Model 400 can address other cards only by mapping a 4-KB "porthole" through the 460Z's address space.<ref>{{cite journal|title=OSI 460Z CPU Expander|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=August 1977|issue=8|page=15|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-08_8/page/15/}}</ref>

===Challenger I (1976)===
Ohio Scientific's first Challenger computer system, retrospectively called the Challenger I,<ref>{{cite journal | last=Smith | first=Stephen P. | date=April 1978 | url=https://archive.org/details/sim_byte_1978-04_3_4/page/150/ | title=Concerning PASCAL: A Homebrew Compiler Project | journal=Byte | publisher=McGraw-Hill | volume=3 | issue=4 | pages=150–151 | via=the Internet Archive}}</ref>{{rp|151}} was introduced in around November 1976.<ref name=iaosichallengeri>{{cite journal | last=Staff writer | date=November 1976 | url=https://archive.org/details/ia-1976-11/page/52/ | title=OSI Challenger | journal=Interface Age | publisher=McPheters, Wolfe & Jones | volume=1 | issue=12 | page=52 | via=the Internet Archive}}</ref> Billed as a tabletop computer,<ref name=newproducts>{{cite journal|title=New Products from OSI|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=June 1977|issue=6|page=8|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-06_6/page/8/}}</ref> the Challenger I borrowed much of its circuitry from the Superboards sold alongside it, but it has a special 48-pin [[S-100 bus]] for expansion which makes use of non-standard [[Molex connector]]s, ostensibly an attempt at making the contacts more reliable.<ref name=Nadeau />{{rp|98}}<ref name=Beamsley /> The Challenger I has four of these special S-100-bus expansion slots.<ref name=newproducts /> Jeffrey Beamsley of ''Micro'' magazine describes the bus as such:
<blockquote>
The 48-pin Ohio Scientific bus is really a model of efficiency. It is made up of four 12-pin Molex-type connectors. Of these 48 pins, only 42 are defined, leaving 6 available for future expansion. The defined pins on the bus include 20 address lines, 6 power lines, 8 data lines, and 8 control lines. The bus supports distributed, fully regulated DC power. The placement of the power lines causes dead shorts on the bus for any board improperly inserted. The Ohio Scientific bus was one of the first microprocessor busses to support bi-directional data lines. It is passively terminated and probably has a bandwidth of 5&nbsp;MHz. It is very inexpensive as far as bus structures are concerned and is classed by Ohio Scientific as proprietary.<ref name=Beamsley>{{cite journal | last=Beamsley | first=Jeffrey | date=December 1980 | url=https://archive.org/details/Micro_NO._31_1980-12_Micro_Ink_US/page/n88/ | title=Up from the Basements | journal=Micro | publisher=Micro Ink | issue=31 | page=87 | via=the Internet Archive}}</ref>
</blockquote>
As stock, the Challenger came with a 1-MHz MOS 6502A microprocessor; optional were a 4-MHz [[MOS 6502C]] and a Motorola 6800.<ref name=Nadeau>{{cite book | last=Nadeau | first=Michael | date=2002 | url=https://books.google.com/books?id=WXZNAAAACAAJ | title=Collectible Microcomputers | edition=Illustrated | series=Schiffer Book for Collectors | publisher=Schiffer Publishing | isbn=9780764316005 | via=Google Books}}</ref>{{rp|98}} The base configuration of the Challenger I contains 1&nbsp;KB of RAM and 1&nbsp;KB of PROM; it can support up to 192&nbsp;KB and 16&nbsp;KB of each respectively.<ref name=newproducts /><ref name=Nadeau />{{rp|98}}

If purchased with 4&nbsp;KB of PROM, Ohio Scientific included a free roll of Microsoft BASIC on [[paper tape]]. The Challenger I comes with a [[bootstrap loader]] built in to the machine that reads from [[paper tape reader]]s such as that built into the [[Teletype Model 33]], which it also supports as a terminal interface due to its inclusion of an ACIA;<ref name=iaosichallengeri /> alternatively a video terminal can be used.<ref name=newproducts /> By mid-1977 a medley of expansion cards and peripherals were available from Ohio Scientific for the Challenger I, including a single or dual [[floppy disk drive]]s (manufactured by GSI in California<ref name=complete />), a cassette drive and interface, a video card, and an external keyboard.<ref name=newproducts /> In January 1978, Ohio Scientific began the Challenger I as part of an integrated bundle, including a custom video terminal using a [[Sanyo]]-manufactured [[Cathode-ray tube|CRT]], a rebranded GSI 110 single floppy drive, and one of two [[Okidata]] [[dot-matrix printer]]s.<ref name=complete>{{cite journal|title=Complete Disk Based System for $2599|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=January 1978|volume=3|issue=1|page=170|via=the Internet Archive|url=https://archive.org/details/sim_byte_1978-01_3_1/page/n173/}}</ref> ''Kilobaud Microcomputing'' called the Challenger I "the first fully assembled mainframe computer which is priced competitively with hobby kits".<ref name=newproducts />

===Ohio Scientific Model 500 (1977)===
The Ohio Scientific Model 500—available as either a single-board computer, as a [[Small form factor (desktop and motherboard)|small-form-factor]] [[desktop computer]] (as the Model 500-1), or as a [[keyboard computer]] (as the Model 500-8)—was announced in July 1977.<ref name=ia>{{cite journal | last=Staff writer | date=July 1977 | url=https://archive.org/details/197707InterfaceAge/page/n95/ | title=A Computer That Thinks in BASIC for Only $298 | journal=Interface Age | publisher=McPheters, Wolfe & Jones | volume=2 | issue=8 | pages=94–95 | via=the Internet Archive}}</ref>{{rp|94–95}} Running a 1-MHz MOS 6502 microprocessor,<ref name=model500 />{{rp|131}} the Model 500 supports up to 4&nbsp;kB of RAM and comes with a 750-byte PROM chip containing one of two [[machine code monitor]]s and four ROM sockets supporting up to 8&nbsp;KB worth of chips.<ref name=ia />{{rp|95}}<ref name=model500 />{{rp|132}} The four 2-KB ROM chips included with the stock Model 500 were manufactured by [[Signetics]] and contain [[Microsoft]]'s official [[Microsoft BASIC|BASIC]] interpreter, occupying all 8&nbsp;KB of ROM. The Model 500 also has a buffered expansion bus and an [[Motorola 6850]] [[UART]] for RS-232 and current-loop serial communications.<ref name=ia />{{rp|95}}<ref name=model500>{{cite journal|title=The OSI Model 500|last=Ruckdeschel|first=F.&nbsp;R.|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=March 1979|issue=27|pages=130–132|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1979-03_27/page/130/}}</ref>{{rp|131}} The Model 500-1's case measured {{convert|12|by|15|by|4|in|cm}}, while the Model 500-8's measured {{convert|15|by|17|by|10|in|cm}}.<ref name=Nadeau />{{rp|98}}

The Model 500 came fully assembled and was interoperable with Ohio Scientific's Model 400 system of peripherals using that computer's backplane,<ref>{{cite journal | editor-last=Ahl | editor-first=David H. | editor-link=David H. Ahl | date=September 1977 | url=https://archive.org/details/CreativeComputingbetterScan197709/page/n15/ | title=OSI Basic Computer | journal=Creative Computing | page=14 | via=the Internet Archive}}</ref> including the Model 440 Super Video board. One of two machine code monitors were supplied: one configured for the Model 500 as used with a terminal for video output, and the other for the computer as used with the Model 440 Super Video board.<ref name=model500 />{{rp|132}} Writing in ''[[Kilobaud Microcomputing]]'', F.&nbsp;R. Ruckdeschel called the Model 500 very cost competitive with the "[[1977 Trinity]]" of the [[Apple II]], [[Commodore PET]], and [[TRS-80]], given that it included Microsoft BASIC like those systems while costing an order of magnitude less.<ref name=model500 />{{rp|131–132}} However, he deemed it "not an 'appliance' computer, but [an] interesting basic microcomputer for the hobbyist", due to the level of involvement needed in setting it up.<ref name=model500 />{{rp|132}}

===Challenger II, 2P (1977)===
[[File:Challenger 2P-IMG 4137.jpg|thumb|Challenger IIP, with optional dual floppy drive unit]]
The Challenger II series, first released in 1977, was offered in a variety of form factors and variants.<ref name=visit>{{cite journal|title=Visit to OSI...|last=Badgett|first=J.&nbsp;Tom|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=August 1979|issue=32|pages=118–123|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1979-08_32/page/120/}}</ref>{{rp|122}} The first two models, the Challenger II (model number IIV, later C2-S2) and the Challenger IIP, were based on Ohio Scientific's Model 500 single-board computer.<ref name=visit />{{rp|122}}<ref name=cd>{{cite journal | last=Staff writer | date=October 1977 | url=https://archive.org/details/bitsavers_computerDe_246610698/page/149/ | title=Increased Capabilities Obtained With Single and Triple Processor Systems | journal=Computer Design | volume=16 | issue=10 | page=149 | via=the Internet Archive}}</ref> The Challenger IIP (also rendered as ''2P'') has a 2-MHz MOS 6502A, while the Challenger II proper has only a 1-MHz 6502.<ref name=Nadeau />{{rp|99}}<ref>{{cite journal|title=Kit Has Basic|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=September 5, 1977|volume=11|issue=36|page=37|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1977-09-05_11_36/page/37/}}</ref> The Challenger IIP has an integral keyboard and [[RF]] video output board but only four of Ohio Scientific's semi-proprietary S-100 expansion bus slots.<ref name=Nadeau />{{rp|99}}<ref name=cii>{{cite journal|title=OSI's Challenger II|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=October 1977|issue=10|page=6|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-10_10/page/6/}}</ref> The II proper meanwhile has eight such S-100 slots but lacks a keyboard or video output—relying on a terminal for interaction—and is built into a desktop form factor.<ref name=visit />{{rp|122}} The II proper also lacks a built-in cassette interface, unlike the IIP.<ref name=completecomp /> Both Challengers came shipped with Microsoft BASIC (the IIP's was included in ROM), had 4&nbsp;KB of RAM, and were compatible with all Challenger I software.<ref name=cii /> A later variant of the II proper includes the built-in cassette interface and video board of the IIP and came shipped with an external full-sized keyboard.<ref name=visit />{{rp|122}}

Video output of the IIP is limited to text, 32 rows of 64 characters, over the RF jack.<ref name=completecomp>{{cite journal|title=OSI's Complete Computer|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=December 1977|issue=12|page=12|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-12_12/page/n11/}}</ref> However, rudimentary graphics can be drawn using 170 special characters in the character generator's code page; characters are also redesignable, for more elaborate custom graphics.<ref name=fully /> Ohio Scientific began selling Challenger 2P's integral video board as a standalone unit for any Challenger system in May 1978, dubbing it the Model 540 video board.<ref name=fully>{{cite journal|title=Fully Assembled Video Display Interface for Ohio Scientific Systems|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=March 1979|volume=4|issue=3|page=250|via=the Internet Archive|url=https://archive.org/details/sim_byte_1979-03_4_3/page/250/}}</ref><ref>{{cite journal|title=CRT Interface Board Built for Ohio Scientific Users|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=May 15, 1978|volume=12|issue=20|page=74|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1978-05-15_12_20/page/74/}}</ref>

In November 1977,<ref name=addsdrive>{{cite journal|title=Ohio Scientific Adds Drive|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=November 28, 1977|volume=11|issue=48|page=49|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1977-11-28_11_48/page/49/}}</ref> Ohio Scientific unveiled the C-D74.<ref name=cd74>{{cite journal|title=OSI Announces 74&nbsp;Megabyte Hard Disk|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=December 1977|issue=12|page=12|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-12_12/page/n11/}}</ref> This was an external hard drive unit that used a 14-inch 74-MB hard disk drive sourced from Okidata.<ref name=cd74 /><ref name=Veit1993 />{{rp|128}} A [[Winchester disk|Winchester]]-style hard disk drive,<ref>{{cite journal|title=New 74 Megabyte Hard Disk|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=February 1978|volume=3|issue=2|page=186|via=the Internet Archive|url=https://archive.org/details/sim_byte_1978-02_3_2/page/n189/}}</ref> it was the first such drive with 12 tracks per cylinder, no head [[Seek time|reseeking]] needed. Ohio Scientific quoted a data transfer rate of 7.3&nbsp;[[Mbit/s]], an [[access time]] of 5&nbsp;{{abbr|ms|milliseconds}}, a single-track seek time of 10&nbsp;ms, and an average random seek time of 35&nbsp;ms.<ref name=cd74 /> The drive was meant specifically for the company's Challenger line and came shipped with the company's OS-74 operating system, an interface card fitting the company's semi-proprietary S-100 slot, and a cable to connect the drive to said card.<ref name=cd74 /> Ohio Scientific later married the drive to their [[#Challenger III|Challenger III]] computer system, incorporating both the drive and the system into a 42-inch tall rack.<ref>{{cite journal|title=Micro Comes Packaged with Winchester Disks|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=September 25, 1978|volume=12|issue=39|page=70|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1978-09-25_12_39/page/n99/}}</ref> Ohio Scientific was the first company to offer a microcomputer with hard drives.<ref name=Veit1993 />{{rp|128}}<ref name=que>{{cite book | last=Taylor | first=Allen G. | date=1986 | url=https://archive.org/details/rbase5000usersgu0000tayl/page/10/ | title=R:BASE 5000 User's Guide | publisher=Que | page=10 | isbn=0880222034 | via=the Internet Archive}}</ref>

Variants of the II and IIP with external [[8-inch floppy disk|8-inch floppy]] disk drive units were introduced in April 1978.<ref name=twofloppies>{{cite journal|title=Two Floppies Boost Challenger Options|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=April 24, 1978|volume=12|issue=17|page=61|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1978-04-24_12_17/page/61/}}</ref> These systems were "unbundled"—lacking an external case and shipped without a power supply.<ref>{{cite journal|title=New Unbundled Floppy Disk Based Computer System|last=|first=|journal=Byte|publisher=McGraw-Hill|date=October 1978|volume=3|issue=10|page=208|via=the Internet Archive|url=https://archive.org/details/sim_byte_1978-10_3_10/page/n213/}}</ref> Ohio Systems issued an external dual [[5.25-inch floppy disk|5.25-inch floppy]] drive unit for the Challenger II by 1979.<ref name=visit />{{rp|122}} Starting in September 1977, Ohio Scientific shipped all Challenger systems ordered with floppy disk drives with OS-65D, the company's own [[disk operating system]] which included the filesystem, BASIC, an assembler, a disassembler, a [[line editor]], and an extended debugger. Through the use of [[Overlay (programming)|overlay]]s, OS-65D never occupies more than 12&nbsp;kB of RAM. It supports dual drive configurations and sequential and random file access, while its BASIC implementation allows [[Linker (computing)|linked]] code.<ref>{{cite journal|title=New Disk Operating System OS-65D|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=September 1977|issue=9|page=9|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-09_9/page/n10/}}</ref>

===Challenger III (1977){{anchor|Challenger III}}===
The Challenger III was released alongside the Challenger II in 1977.<ref name=cd /> It was a desktop computer featuring three microprocessors—a MOS 6502A,<ref name=cbn>{{cite journal|title=Challenger systems get three languages|last=Staff writer|journal=Computer Business News|publisher=CW Communications|date=November 27, 1978|volume=1|issue=4|page=12|via=the Internet Archive|url=https://archive.org/details/sim_micro-marketworld_1978-11-27_1_4/page/n13/}}</ref> a Zilog Z80, and a [[Motorola 6800]]—on one board. This combination of processors allowed the computer to run virtually all software for microcomputers on the market at the time of its release.<ref name=osiiii>{{cite journal|title=OSI Challenger III|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=November 1977|issue=11|page=10|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1977-11_11/page/10/}}</ref> Only one processor can be active at a time, preventing it from computing in parallel, but software interrupts allow programs to switch from processor to processor on the fly.<ref name=Bassett1980 />

Ohio Scientific oriented the Challenger III as a development kit for students of computer science wanting to learn how to program for all three processor; as a small business or industrial machine, for organizations wanting to consolidate mission-critical applications for multiple platforms onto one unit; and for the extreme hobbyist.<ref name=osiiii /> An external, single-sided (later double-sided), dual 8-inch floppy drive unit was available for the Challenger III,<ref>{{cite journal|title=System Tests Applications|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=November 7, 1977|volume=11|issue=45|page=54|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1977-11-07_11_45/page/53/}}</ref><ref>{{cite journal|title=Disk Option Doubles Memory of C3 Micro|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=May 7, 1979|volume=13|issue=19|page=58|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1979-05-07_13_19/page/58/}}</ref> as was the C-D74 hard drive unit. Ohio Scientific was keen to match the Challenger III with the C-D74, offering both in a 74-inch tall rack-mount case as a complete system christened the C3-B<ref name=Bassett1980 />—the first microcomputer system to include a hard drive.<ref name=Veit1993 />{{rp|128}}<ref name=que /> A variant of the C3-B with a cheaper, lower-capacity 24&nbsp;MB drive was released by 1979.<ref name=visit />{{rp|122}} The C3-B was particularly useful as a database manager serving multiple client terminals. To this end, Ohio Scientific provided a serial I/O board called the CA-10, allowing up to sixteen terminals to connect to the Challenger III.<ref name=Bassett1980>{{cite journal | last=Bassett | first=S.&nbsp;B. | date=March 31, 1980 | url=https://books.google.com/books?id=bz4EAAAAMBAJ&pg=PT17 | title=Taking on the Minis: Beginning of a Revolution | journal=InfoWorld | publisher=IDG Publications | volume=2 | issue=4 | page=14, 18 | via=Google Books}}</ref>{{rp|18}}<ref>{{cite journal|title=Ohio Scientific Adds I/O Boards|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=March 27, 1978|volume=12|issue=13|page=69|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1978-03-27_12_13/page/n120/}}</ref> A version of the Challenger III with integrated CA-10 and dual 8-inch floppy drives (but without the integral keyboard) was introduced as the C3-OEM in late 1978.<ref>{{cite journal|title=New Microcomputer System from OSI|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=December 1978|volume=3|issue=12|page=224|via=the Internet Archive|url=https://archive.org/details/sim_byte_1978-12_3_12/page/n231/}}</ref>

===Superboard II, Challenger 1P (1978)===
[[File:Ohio Scientific Superboard.jpg|thumb|right|Superboard II residing inside a homemade wooden case]]
Released in fall 1978, the Superboard II featured a MOS 6502, 8&nbsp;KB BASIC in ROM, a BIOS and machine code monitor in separate ROM, 8&nbsp;KB of [[static RAM]], a cassette interface, and, most notably, a built-in keyboard soldered to the board. Ohio Scientific billed it as the first microcomputer integrated onto one single circuit board, owing to the soldered-on keyboard.<ref name=introduces>{{cite journal|title=OSI Introduces Single-Board Computer|last=Staff writer|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=November 1978|issue=23|pages=9–10|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1978-11_23/page/9/}}</ref><ref name=bows>{{cite journal|title=One-Board System Bows from Ohio Scientific|last=Staff writer|journal=Computerworld|publisher=CW Communications|date=November 13, 1978|volume=12|issue=46|page=85|via=the Internet Archive|url=https://archive.org/details/sim_computerworld_1978-11-13_12_46/page/85/}}</ref> The company introduced it alongside the Challenger 1P, essentially the same as the Superboard II but enclosed in a case and including a power supply.<ref name=introduces /><ref name=bytesbii /> Optional for each were an 24&nbsp;KB expansion RAM and floppy disk drive interface board, for supporting an external dual 5.25-inch floppy drive as well as a printer or modem.

The entire Superboard II measures {{convert|12|by|14.5|in|cm}}.<ref name=kbsbii />{{rp|66}} Ohio Scientific were able to reduce the chip count by using cutting-edge [[Large scale integration|LSI]] chips, which combined many support chips onto one integrated circuit.<ref name=bows/> All components on the board—57 ICs, several passives, the keyboard components, and a fuse—were soldered by hand; the board is free of solder mask and board legends.<ref name=kbsbii />{{rp|66}} A clone of the Superboard II was sold in the United Kingdom as the [[Compukit UK101]].<ref>{{cite web | last=Fitzpatrick | first=Jason | date=2012 | url=https://www.computinghistory.org.uk/det/8099/Compukit-UK101/ | title=Compukit UK101 | publisher=Centre for Computing History | archiveurl=https://web.archive.org/web/20230109082713/https://www.computinghistory.org.uk/det/8099/Compukit-UK101/ | archivedate=January 9, 2023}}</ref>

Bruce S. Chamberlain, writing in ''Kilobyte Microcomputing'', praised the Superboard II's BASIC interpreter for its speed and called the system overall "less expensive than comparable systems" and "the best buy available for both beginner and expert. ... It is also easier and less expensive to expand than other computer systems".<ref name=kbsbii>{{cite journal|title=OSI's Superboard II|last=Chamberlain|first=Bruce S.|journal=Kilobaud Microcomputing|publisher=Wayne Green, Inc.|date=July 1979|issue=31|pages=66–70|via=the Internet Archive|url=https://archive.org/details/sim_microcomputing_1979-07_31/page/n7/}}</ref> ''Byte''{{'s}} Christopher Morgan similarly called it "an excellent choice for the personal computer enthusiast on a budget".<ref name=bytesbii>{{cite journal|title=The Superboard II|last=Morgan|first=Christopher|journal=Byte|publisher=McGraw-Hill|date=May 1979|volume=4|issue=5|pages=50–51|via=the Internet Archive|url=https://archive.org/details/sim_byte_1979-05_4_5/page/n53/}}</ref>

===Challenger 4P (1979)===
[[File:OSI Challenger 4P.jpg|thumb|Challenger 4P]]
The Challenger 4P (4P MF), released in late 1979, was a keyboard computer like the Challenger IIP.<ref name=popular />{{rp|107}} Like all Challengers before it, the 4P ran off a 6502 microprocessor.<ref name=Nadeau />{{rp|99}} It was the first in the line to feature native color graphics, displaying 16 color simultaneously in bitmap graphics mode.<ref name=popular>{{cite journal | last=Shapiro | first=Neil | date=August 1980 | url=https://books.google.com/books?id=V9QDAAAAMBAJ&pg=PA80 | title=New Computers Can Talk, Control Your House, and Sing | journal=Popular Mechanics | publisher=Hearst Corporation | volume=154 | issue=2 | page=80–81, 106–107 | via=Google Books}}</ref>{{rp|80}} In text mode, it displays 64 columns by 32 rows.<ref name=byteciv>{{cite journal|title=C4P MF Personal Computer|last=Staff writer|journal=Byte|publisher=McGraw-Hill|date=December 1979|volume=4|issue=12|page=252|via=the Internet Archive|url=https://archive.org/details/sim_byte_1979-12_4_12/page/252/}}</ref> As with the Challenger II, characters in the code page are redesignable, allowing for complex shapes to be drawn even in text mode.<ref name=popular />{{rp|107}} The computer came with 24&nbsp;KB of RAM stock, expandable to 48&nbsp;KB. A DAC interface allows the generation of sound, voice output, analog joystick interfaces, and, unusually, a home automation interface.<ref name=byteciv /><ref>{{cite journal | last=McClure | first=Jim | date=October 1980 | url=https://archive.org/details/CreativeComputingbetterScan198010/page/n18/ | title=The C2-4P Ohio Scientific Computer | journal=Creative Computing | volume=6 | issue=10 | pages=17–23 | via=the Internet Archive}}</ref> The Challenger 4P was very adept at this latter task, implementing the [[X10 (industry standard)|X10 industry standard]] protocol for home automation. Through special software, the computer can control up to 16 lights and appliances in the house.<ref name=popular />{{rp|81}} A "background mode" allows the user to run other applications in the foreground, while a timer resident in memory keeps track of X10 schedule and shuts appliances on and off accordingly.<ref name=popular />{{rp|106}}

===C1P (MF) Series II (1980)===
The C1P Series II was a redesign of Ohio Scientific's Challenger 1P with a vastly different case design made with a plastic shell, over top of the standard metal case. The 1P incorporates the DAC of the Challenger 4P to allow the computer to generate sound and music. The computer came stock with Microsoft 8K BASIC IN ROM, and 8KB of Static RAM, and it could have been expanded to have the home automation features of the 4P with the purchase of 630/10 expansion card. The C1P MF was a variant of the computer that came packaged with a dual 5.25-inch floppy drive unit and OS-MDMS, a small database management system.<ref name=Nadeau />{{rp|100}}<ref>{{cite journal | last=Ahl | first=David H. | author-link=David H. Ahl | date=September 1980 | url=https://archive.org/details/CreativeComputingbetterScan198009/page/n27/ | title=Random Ramblings: The Consumer Electronics Show | journal=Creative Computing | volume=6 | issue=9 | pages=16–34 | via=the Internet Archive}}</ref>

== See also ==
* [[List of early microcomputers]]

==References==
{{Reflist}}

==External links==
{{Commons category|Ohio Scientific}}
* [http://osi.marks-lab.com/ Mark Spankus's archive of Ohio Scientific and Compukit documentation]
* [http://www.osiweb.org osiweb.org]&nbsp;– Ohio Scientific repository and forum

{{Hard disk drive manufacturers}}
{{Authority control}}

[[Category:Early microcomputers]]
[[Category:1975 establishments in Ohio]]
[[Category:1980 mergers and acquisitions]]
[[Category:1983 disestablishments in Ohio]]
[[Category:American companies established in 1975]]
[[Category:American companies disestablished in 1983]]
[[Category:Aurora, Ohio]]
[[Category:Computer companies established in 1975]]
[[Category:Computer companies disestablished in 1986]]
[[Category:Computer storage companies]]
[[Category:Defunct computer companies of the United States]]
[[Category:Defunct computer hardware companies]]
[[Category:Defunct computer systems companies]]
[[Category:Defunct software companies of the United States]]
[[Category:Hudson, Ohio]]
[[Category:Software companies established in 1975]]
[[Category:Software companies disestablished in 1986]]
[[Category:6502-based home computers]]
[[Category:Companies based in Akron, Ohio]]