History of Ohio Scientific Incorporated

Ohio Scientific Instruments began operations in Hiram, Ohio around 1975. In Byte #6 there was an advertisement for a 6502 based computer trainer for US$99. This could be traded in on an OSI Superboard kit, or for US$10, for a blank circuit board and a set of instructions for these computers designed by Mike and Charity Cheiky, founders and owners of OSI.

Mike and Charity demonstrated their 400 board at the Trenton NJ Computer Show of 1976, showing how it could be built with either a 6502 or a 6800 processor. This board had space for 8 memory chips, 2102, to provide 1024 bytes. OSI also had video boards and memory boards, and you could buy the bare boards for US$29. The 400 series boards were designed on the basis that cheap is better, and the 420 memory board took that to the nth degree. No sockets for the memory chips. The board was single sided. The bus was done with Molex pins.

One really nice feature of the OSI boards was they were large and uncluttered, easy to build, and didn't produce as much interference as the more compact designs others used. The top of the line model at this point cost US$675. What is more, you could buy 16K memory boards, an unheard of amount of memory in those days.

The OSI Challenger computer was one of the first personal computers to be supplied with a floppy disk drive, one of the first that could handle multiple users, and the very first to use a Winchester hard drive. This was at a time when computers like the Apple II and TRS-80 were still using cassette tapes.

They had a wide range of 6502 based computers by 1977, ranging from the bare 500 board with 8K BASIC and 4k RAM at US$298, through the CII with a case for US$598, an 8 inch floppy model with 16k of RAM for around US$2000, the CIII with 32k of RAM, two 8 inch floppy drives and serial I/O for US$3481, to a US$6000 addition with a 74 MB hard drive.

OSI provided serial terminal systems, 24x24 character displays, up to 64x32 character displays, sound output as standard. They had voice input boards with a Votrax module, X10 AC control interface boards, joystick boards, ADC and DAC boards, prototyping cards, home security interfaces, a telephone interface, and an eprom burner. Probably the larest range of boards ever to come from one small manufacturer

Unfortunately, the OSI software support was pathetic. Their attitude seemed to be that they produced computers, not manuals. Towards the end they did have three excellent hardware manuals, produced by SAMS as part of their "Photofacts" series. OSI were bought out by MA-COM, who got rid of Mike Cheiky, dropped the hobby systems, and eventually went bankrupt.

 

Ohio Scientific Incorporated company datas

Ohio Scientific Inc. (old address)
1333 S. Chillicothe Road
Aurora, OH 44202

Founder Mike Cheiky

Mar 1981 OSI is sold to M/A-Com Inc. of Burlington MA.
OSI will concentrate on business systems.
Mike Cheiky will remain as VP of Development.
May 1982 OSI name is changed to M/A-Com
Office Systems Inc.

High End Model Challenger 4P MF
-----------------------------------------------------
Ram 24K expandable to 48K
Display 64 chars/line 32 lines/screen, 512x356
Disk 1 mini floppy expandable to 2
Price new $1695

 

Ohio Scientific computer history

Superboard II
CPU: 6502
PRICE: US $280
RAM: 4K initial, 32K max
ROM:
DISPLAY: 48 columns x 12 lines
OPERATING SYSTEM: ROM


Model Challenger 1P
CPU: 6502
PRICE: US $350
RAM: 8K initial, 32K total
ROM: 8K
STORAGE: Optional cassette
OPERATING SYSTEM: ROM
VDU: B/W TV, Monitor
Basically the C1P was a superboard with chassis and power supply.


Model Challenger 1P MF
CPU: 6502
PRICE: US $1000
RAM: 20K initial, 32K total
STORAGE: 5 1/4" floppy diskette
OPERATING SYSTEM: DOS


Model Challenger 4P
CPU: 6502
RAM: 8K initial, 32K total
STORAGE: Optional
DISPLAY: 64 columns x 32 lines
COLOURS: Optional
YEAR: 1979
OPERATING SYSTEM: ROM


Model Challenger 4P DF
CPU: 6502A
PRICE: US $????
RAM: 48K initial, 96K total
ROM:
CLOCK:
STORAGE: 8" floppy diskette
Capacity:
OPERATING SYSTEM: DOS


Model Challenger 4P MF
CPU: 6502A
PRICE: US $1695
RAM: 24K initial, 48K total
ROM:
CLOCK: 2MHz
COLOURS: 8 (2 tones each)
DISPLAY: 64 coloumns x 32 lines
STORAGE: 5 1/4" floppy diskette
Capacity: 90K
VDU: TV, Monitor
SOUND GENERATOR: Yes
VOICES: 4
OCTAVES: 3
OPERATING SYSTEM: DOS

 

Some 6502 Microprocessor history

An overview about the 6502 CPU instruction set

MOS Technologies
A microprocessor design company started by some ex-Motorola designers, shortly after the Intel 8080 and Motorola 6800 appeared, in about 1975. MOS Technologies introduced the 650x series, based on the Motorola 6800 design, though they were not exact clones for legal reasons.
The design goal was a low-cost (smaler chip) design, realized by simplifying the decoder stage. There were no instructions with the value xxxxxx11, reducing the 1-of-4 decoder to a single NAND gate. Instructions with the value xxxxxx11 actually executed two instructions in paralell, some of them useful.
The 6501 was pin-compatible with the 6800 for easier market penetration.
The 650x-series had an on-chip clock oscillator while the 651x-series had none.
The 6510 was used in the Commodore 64, released September 1981 and MOS made almost all the ICs for Commodore's pocket calculators.
The PET was an idea of the of the 6500 developers. It was completly developed by MOS, but was manufactured and marketed by Commodore. By the time the it was ready for production (and Commodore had cancelled all orders) MOS had been taken over by Rockwell (Commodore's parent company). Just at this time the 6522 (VIA) was finished, but the data sheet for it was not and its developers had left MOS. For years, Rockwell didn't know in detail how the VIA worked. .

Floppy Disk Drive for OSI