Nova

processor A minicomputer(?), introduced some time before

1978, with four 16-bit accumulators, AC0 to AC3 and a 15 bit

program counter. A later model also had a 15-bit stackpointer and frame pointer. AC2 and AC3 could be used for

indexed addresses 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 access 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(?) cycle time for each. The Nova originally

used core memory though later on they gained dynamic RAM.

Like the PDP-8, the Data General Nova was also copied, not

just in one, but two implementations - the Data GeneralMN601 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 Intel8008).

[Date, speed, mini?]

(1996-03-01)