page_title: Ohio Scientific
section_title: Products
hierarchical_section_title: Ohio Scientific / Products
caption_attribution_description: English: Ohio Scientific Superboard. Picture was taken by myself of a computer that I purchased in the mid-70's. The manufacturer is no longer in existence. The picture may be used freely if attributed to myself, John DeRosa
context_page_description: Ohio Scientific Inc. was an Ohio-based computer company that built and marketed microcomputers from 1975 to 1981. Their best-known products were the Challenger series of microcomputers and Superboard single-board computer kits.
context_section_description: One of their first products, launched in 1977, was the OSI Model 500 system, a very simple single board computer based on the MOS Technology 6502 microprocessor. It needed an external video monitor as it had an internal character-based video controller and ran Microsoft BASIC. Storage was to any cassette by FSK encoding.
  The Challenger III, introduced in August 1977, had a maximum of 53 KB of static RAM and used 8" 370 KB floppy disks in its dual floppy drive system. It was also sold in an optional 4' high 19" rack mount cabinet with wheels, version C3-B, that included a hard drive. (Ohio was the first company to use a Winchester hard drive in its PCs.) This was intended for an office environment and used a standard computer terminal, like the Hazeltine 1420 (or 1500), which was optionally supplied through factory sales. The terminals were the same ones as used with mainframe computers of that era. With the largest hard drive available, 74MB, the system cost just under $13,000. The least expensive version without the rack or hard drive was $3995 MSRP, a phenomenal performance-to-cost ratio for the time. The Challenger III also had the capability to support non-floppy or hard drive Challenger 2P computers through a simple network using RS-232 links.
  OSI's later products were also 6502-based, the Superboard II, Challenger 1P, Challenger 2P, Challenger 4P and Challenger 8P, introduced in 1979 and discontinued in 1981.
  Original Ohio Scientific motherboard designs used 7400-series  TTL  chips. Instead of using a floppy disk controller IC, OSI used a Motorola MC6850 ACIA Serial Port ACIA chip and a Motorola MC6821 (PIA) chip for the Disk Drive Controller, which made OSI 8" & 5-1/4" Floppy Disks unreadable by other computer systems.
   
  The Superboard II was the least expensive computer, retailing for around the $279 price range, with an onboard BASIC programming language. It came without a case or power supply. It was a single board computer with the keyboard integrated on the same printed circuit board. It was shipped with 4KB of RAM (upgradable to 8KB), a 2KB BIOS in ROM (known as SYNMON as the ROM was labeled 'SYN600' or 'SYNMON 1.0') and an early version of Microsoft 8K BASIC. OSI 6502 BASIC Version 1.0 Revision 3.2 (c) 1977 By Microsoft.
  The version OSI C1P / 600D Superboard II (occasionally advertised as the 'Colorboard') featured an unpopulated socket for an extra 1k × 4-bits of video RAM to hold character color information. The implementation of this was detailed in the OSI user group newsletter which was published around four times a year. The 600D also featured two video modes: 32×32 (~24×24 visible) for 'graphics', or 64×16 (~48×15 visible) for text where each text line had a blank line between it and the next. The mode could be selected by a poke to the keyboard register. The computer couldn't write to the video memory without glitching the display. There was an add-on graphics card for the Superboard that would display 256 by 256 pixels. It came with software to draw 3D graphics.The keyboard polling register (a simple 8-bit TTL Latch) was also used as a very crude digital-to-analog converter by means of a resistor ladder connected to an 'audio out' socket to the right of the keyboard.
  Unusual for the day, but reflecting the home built nature of personal computers of this era, the company supplied full crude schematics of their hardware. This allowed the Computer Hobbyist or 3rd-party companies to create after-market field modifications, such as increased clock speed, increasing the cassette tape drive storage speed, and increased video line length, as well as reverse video (white screen with black text).
  The C2P video systems did not have color graphics like the Apple II, just upper- and lower-case text, and some pseudo graphical characters, (comparable to the "PETSCII" character set of the Commodore PET) for drawing lines and supporting simple games. 
  The Challenger 4P (C4P-MF) came with color display output capability, using a TV or TV converted to have direct video input, and dual 5¼" floppy drives. It also had t
caption: Superboard II - single board computer with home built case opened
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