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From: fuka@parsec.UUCP
Newsgroups: net.arch
Subject: Re: uP architecture and the NOVA - (nf)
Message-ID: <2402@uiucdcs.UUCP>
Date: Tue, 19-Jul-83 00:15:54 EDT
Article-I.D.: uiucdcs.2402
Posted: Tue Jul 19 00:15:54 1983
Date-Received: Wed, 13-Jul-83 08:25:33 EDT
Lines: 23

#R:orca:-135800:parsec:32800002:000:1047
parsec!fuka    Jul 11 16:12:00 1983

As a former programmer for Data General, I agree with most of what
orca!andrew has to say about the Nova.  It WAS a real pain to write
software for, but the simple architecture made it cheap to produce out
of TTL in those days, which made it cheap to sell.  Just like the RISC,
it was also fast (for the times) because it was such a simple
instruction set to decode.  If you think about the concepts in RISC,
the Nova was actually a pretty far-sighted machine.  That doesn't mean
that I'd ever want to program one again, however.

One minor point:  The sixteenth bit of Nova addresses WAS used -- it
was an indirect bit, which allowed for n-way indirection of memory
references.  Any indirect reference which found an indirect pointer
which had this bit set would cause a second level of indirection.  Some
knock-off Nova manufacturers (AMPEX?) used this 'extra' bit to
implement a doubling of the address space (but only through indirect
addressing).

					Kent Fuka
					Parsec Scientific Computer Corp.
					{allegra|ihnp4|uiucdcs}!parsec!fuka