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nova 音標拼音: [n'ovə] n. 新星 新星 nova n 1: a star that ejects some of its material in the form of a cloud and become more luminous in the processNova \ No" va\ ( n[= o]" v[. a]), n.; pl. L. { Novae} ( n[= o]" v[= e]), E. { Novas} ( n[= o]" v[. a] z). [ L., fem. sing. of novus new.] ( Astron.) A star which suddenly increases in brightness thousands of times, then fades back to near its original intensity. It may appear as a " new" star if its original brightness was too low for routine observation. A star which suddenly increases in brightness to many millions of times its original intensity is a { supernova}, and the postulated mechanisms for the increases of brightness of novae and supernovae are different. Note: The most important modern novae are: { No" va Co* ro" nae Bo` re* a" lis}[ 1866]; { No" va Cyg" ni}[ 1876]; { No" va An* dro" me* dae}[ 1885]; { No" va Au* ri" gae}[ 1891- 92]; { No" va Per" se* i}[ 1901]. There are two novae called { Nova Persei}. They are: ( a) A small nova which appeared in 1881. ( b) An extraordinary nova which appeared in Perseus in 1901. It was first sighted on February 22, and for one night ( February 23) was the brightest star in the sky. By July it had almost disappeared, after which faint surrounding nebulous masses were discovered, apparently moving radially outward from the star at incredible velocity. [ Webster 1913 Suppl. PJC] 40 Moby Thesaurus words for " nova": Beehive, Cepheid variable, Hertzsprung- Russell diagram, Hyades, Messier catalog, NGC, Pleiades, Seven Sisters, absolute magnitude, binary star, black hole, double star, dwarf star, fixed star, giant star, globular cluster, gravity star, magnitude, main sequence star, mass- luminosity law, neutron star, open cluster, populations, pulsar, quasar, quasi- stellar radio source, radio star, red giant star, relative magnitude, sky atlas, spectrum- luminosity diagram, star, star catalog, star chart, star cloud, star cluster, stellar magnitude, supernova, variable star, white dwarf star 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}).
[Speed, mini?]
(2003-10-23)
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