nova

nova: see supernova; variable star.

---

nova

Any of a class of stars whose luminosity temporarily increases by several thousand up to a million times normal. Most appear to be close binary stars, one of which is a white dwarf star drawing in matter from the other until it becomes unstable, causing an outburst in which the outer layer of material is shed. A nova reaches maximum luminosity within hours after its outburst and may shine intensely for several days or even a few weeks; it then slowly returns to its former level. The process can repeat at intervals ranging from a few dozen to hundreds of thousands of years. Stars that become novas are usually too faint to see with the unaided eye until their sudden increase in luminosity, sometimes great enough to make them readily visible in the night sky. To observers, such objects may appear to be new stars; hence their name (Latin for “new”). See also supernova.

---

A minicomputer series from Data General. When introduced in 1969, it was the first 16-bit mini to use four CPU accumulators, quite advanced for its time. Novas and its RDOS operating system were used extensively in the OEM marketplace.

---

(processor)

Nova - A minicomputer(?) introduced by Data General in 1969, with four 16-bit accumulators, AC0 to AC3, and a 15-bit program counter. A later model also had a 15-bit stack pointer and frame pointer. AC2 and AC3 could be used for indexed addressing and AC3 was used to store the return address on a subroutine call. Apart from the small register set, the NOVA was an ordinary CPU design. Memory could be accessed indirectly through addresses stored in other memory locations. If locations 0 to 3 were used for this purpose, they were auto-incremented after being used. If locations 4 to 7 were used, they were auto-decremented. Memory could be addressed in 16-bit words up to a maximum of 32K words (64K bytes). The instruction cycle time was 500 nanoseconds(?). The Nova originally used core memory, then later dynamic RAM. Like the PDP-8, the Data General Nova was also copied, not just in one, but two implementations - the Data General MN601 and Fairchild 9440. Luckily, the NOVA was a more mature design than the PDP-8. Another CPU, the PACE, was based on the NOVA design, but featured 16-bit addresses (instead of the Nova's 15), more addressing modes, and a 10-level stack (like the Intel 8008).