The System 0 was one of the last and lowest cost system from Cromemco. The basic unit was a six-slot S-100 board with an all-in-one CPU board and power supply. The smallest system featured 1 KB RAM and 4 KB ROM monitor, as well as serial and parallel ports. The bigger system, designated Zero/D, had 64 KB of RAM and separate dual floppy disc drives unit. It was sold with CP/M operating system, printer drivers and self test diagnostics. It was also possible to use a version of Unix called Cromix if a further 64 KB of RAM was installed.