Data General Eclipse

The Data General Nova was intended to outperform the PDP-8 while being less expensive, and in a similar fashion, the Eclipse was meant to compete against the larger PDP-11 computers. It kept the simple register architecture of the Nova but added a stack pointer which the Nova lacked. The stack pointer was added back to the later Nova 3 machines in 1975 and also used on the later 32-bit Data General Eclipse MV/8000. The AOS operating system was quite sophisticated, advanced compared to the PDP-11 offerings, with access control lists (ACLs) for file protection.

Production problems with the Eclipse led to a rash of lawsuits in the late 1970s, after new versions of the machine were pre-ordered by many DG customers and then never arrived.[1] After over a year of waiting, some decided to sue the company, while others simply cancelled their orders and went elsewhere.[1] It appeared that the Eclipse was originally intended to replace the Nova outright, also evidenced by the fact that the Nova 3 series released at the same time was phased out the next year. However, strong continuing demand resulted in the Nova 4, perhaps as a result of the continuing problems with the Eclipse.

The original Cray-1 system used an Eclipse to act as a Maintenance and Control Unit (MCU). It was configured with two Ampex CRTs, an 80 MB Ampex disk drive, a thermal printer, and a 9-track tape drive. Its primary purpose was to download an image of either the Cray Operating System or customer engineering diagnostics at boot time. Once booted, it acted as a status and control console via RDOS station software.