Welcome to our deep dive into the Ohio Scientific C4P, a formidable yet often overlooked star of the late 1970s microcomputer revolution. While the Superboard II brought computing to the masses as a single-board kit, the C4P represented OSI’s vision of a more expansive, professional-grade system—packed with potential for business, education, and serious hobbyists.
Released in 1978, the C4P (sometimes called the Challenger 4P) was built around the legendary MOS 6502 CPU but distinguished itself with a robust chassis, full-sized keyboard, and expansion capabilities that put it in competition with early Apple and Commodore systems. With support for floppy drives, parallel/serial interfaces, and up to 48KB of RAM, it was a versatile machine that bridged the gap between hobbyist curiosity and real-world utility.
I picked up a OSI542 Rev C keyboard PCB a while ago so finally got around to making a case to put it in.
Working great with the 8-slot backplane and the 505-CPU boad plus 540C Video board and a DIY 32k RAM card.
A mock up case for the 8-slot backplane board and test fitting a power supply with a OSI400 board installed.
After a quick paint job and meanwell power supply install it’s a C4P with external keyboard with matching colours.
Now with a D13 data seperator installed I attached a clone gotek to boot from disk.