Ohio Scientific computers

Hardware theme

Computers of various intercompatibility by Ohio Scientific active from 1975 to 1981.

The first video game about Ohio Scientific computers was released in 1969.

Note that the flowing cart is dated and incomplete.
OSI Model 300 "trainer" Sold in 1976. 6502 and 6810.
OSI Model 400 6501, 6502 or 6800.
OSI Model 500 was a displayless single board computer based on the MOS 6502. It required being accessed by an external terminal.
OSI Model 502 a 500 variant used in C4P and C8P systems.
OSI Model 510 "Challenger III","C3". Only vaguely related to the later Challenger series. August 1977. 6502, 6800, and Z80 (software switchable). Maximum 53KB of static RAM. Dual 8" floppy disks. Optional hard drive up to 74MB. Also required a terminal.
OSI Model 600 "Superboard II" No Case or power supply. 6502 or 6800. OSI BASIC based on Microsoft 8K BASIC. 4-8KB RAM. Keyboard on the motherboard. 8" floppies or standard 5¼ floppies. OS-65 "Disk Operating System".
Challenger 1P. Basically a Superboard II in consumer ready product. 6502 or 6800. OSI BASIC. 8" floppies or standard 5¼ floppies. OS-65 "Disk Operating System".
Challenger 2P. 6502. OSI BASIC. 8" floppies or standard 5¼ floppies. OS-65 "Disk Operating System".
Challenger 4P (4P/MF). Sold in 1979. [email protected] or [email protected] 8-32KB RAM. Color TV output. 8" floppies or standard 5¼ floppies. Cassette interface. Dual joystick interface and two joysticks. Two keypad interfaces. Modem port, Printer port, 3 I/O bus ports. CAssette port, audio out, audio in, DAC port, AC control port, and monitor out (TV).
Challenger 8P. 6502. 8" floppies or standard 5¼ floppies.

Briel Computers Superboard III is a modern take on the Superboard II design (on which the Challenger series is based). It features a CPU that is made up of 32 CPUs running in parallel with shared 32K memory. It has several interfaces for easily communicating with e modern personal computer. For nostalgia the keyboard is built on the board (even though later Challenger series machines had separate keyboards :P ) However, nostalgia fails to reproduce having the RESET key next to the ENTER key (where it is very easy to accentually destroy all current work ). Most interesting of all is the 100% compatible with all the old OSI accessories.

OSI Model 440B Video board 128x128x4

OSI Model 460Z This was a 3 CPU expander board to add a Z-80, a 6100, and one of the following: a Signetics 2650, Fairchild F8, or RCA COSMAC 1802. Software switchable with advanced debugging options.

OSI Model Model 560Z expander board for z80 and 6100. Allowed full PDP-8 emulation (software required). Could also run 8080 code.

Reported CPU range with OSI and 3rd Party add-ons:
MOS 6501
MOS 6502*
MOS 6800
MOS 6810
MOS 6809**
MOS 6100
Zilog z80
Intel 8080
Signetics 2650
Fairchild F8
* OSI information on the Internet revolves around 6502. All available applications seem to be 6502. Even C3P specific software is 6502. Although the 6800 and 6809** were offered standard from OSI, and a z80 and 6800 and add-in cards supported many other CPUs, it seems the popularity of using 6502 overwhelmed the use of any other CPU in OSI machines. Of course the 6502 would be more popular than the 6800. It was widely seen as an equally capable but cheap clone of the 6800 (some even insisted it was superior).

Latinized roman numerals and plus symbols were alternately used in the names Challenger II+, Challenger IV, Challenger VIII. Also, model designations were sometimes confusingly named ("C2-8P", was actually a Challenger II+ with 8 expansion slots)

OSI computers had a wide variety of analogue sensor interfaces. They are used to monitor and operate nuclear power plants due to their durability and reliability.

Various color and 256x256 graphics and audio out upgrades were available. There was even a 3D graphics upgrade.
A Votrax module can be used for speech synthesis. Some models used the the less common blue phosphor display.

Math co-processor upgrades for OSI computers were available as early as August, 1981.

Most systems (or boards) came clocked to 1MHz unless a "GT" model was ordered (an option for any model). But, home users could easily modify any OSI to run at 2 MHz. The factory GT models was properly clocked and trouble free. The home modification involved bending a pin from the CPU and soldering it to a component over 1" away on the motherboard. This was a completely unintended use of a completely unrelated clock. The physics involved in sending a clock signal that far prevents this from bing a consistent clock speed even if silver wire is used. This would not cause alien invaders in games to speed up and slow down unpredictably but could prevent time related functions from performing correctly, such as in a spreadsheet application. This would also overheat 2114 memory chips in the system, unless a fan was added.

OSI had a unique arrangement for customers. IN 1976, for $99 they were sent parts for a "trainer computer" to solder together and test to verify it worked correctly. Customers could trade a working TC and $10 for a complete Superboad II system (worth well more than $109). Customers learned how to build a computer and got a discounted system. OSI got cheap labor to assemble their Model 300 boards.

The C1P model was faster and had more memory than a TRS-80 Model 1. It lacked a graphics mode but included an extended character set for making graphics in text mode. It lacked an understandable manual (if you weren't a geek) and lacked a BASIC tutorial (whereas the TRS-80 came with somewhat user friendly manuals and text-books for BASIC or other subjects) The C1P cost just a bit less than a TRS-80.

Also sold under the name "OSITRON". The C4P had a variant that sold in Sears department stores. Compukit UK101 is a 100% compatible clone.

From looking at Ohio Scientific's brochures, one might get the impression it was all business monochrome text boring. But it wasn't:

The keyboards were built right on the circuitboards for some models:

Ohio Scientific provided full schematics for _everything_ they sold. Contents of the on-board ROM chips were and are widely available through otherwise legitimate vendors. This means clones were easy to make. A child could/can order everything to assemble and use an OSI clone without leaving home. OSI seemed unconcerned about the contents of their BIOS ROM chips and indeed catered to computer hobbyists who routinely ignored such inconveniences as copyright. This atmosphere attracted developers and companies to sell software for the OSI despite the existence of the vastly more popular home computer trinity of the era (Commodore PET, TRS-80, Apple ][). No clone companies seemed to have competed with OSI in North America, but companies in Europe sold many OSI clones. of course the BIOS was only half of the OSI's ROMs, The other 8K of was based on Microsoft BASIC. OSI began selling hardware about the same time Bill Gates wrote his famous letter to Computer Hobbyists and set the industry toward a fully proprietary environment. But it seems Microsoft never took action specifically against the OSI community. None of this prevented several enterprising individuals from making replacement ROMs for OSI machines although these efforts were probably motivated toward improving computers rather than copyright concerns.

Jeff Tranter has made a source code to create a ROM, including BASIC, for the Ohio Scientific Superboard II (Challenger 1P, Model 600). His code includes fixes for known bugs such as improper error messages and faulty garbage collection.
Ohio Scientific C1PGames targeting the Ohio Scientific C1P computer system (may work on other OSI machines with or without hacks).1979 / 198261 games
Ohio Scientific C2PGames targeting the Ohio Scientific C2P computer system (may work on other OSI machines with or without hacks).1978 / 198193 games