info-vax@ucbvax.ARPA (06/04/85)
From: sasaki@harvard.ARPA (Marty Sasaki)
I find the rumors about things truly amazing, especially the microVAX
III. A recent note mentioned that the next microVAX will not have a
Q-bus, but might use a CI or a UNIBUS. This is very unlikely.
The Q-bus is a pretty fast bus, almost twice as fast as a UNIBUS in
practical applications and use. It has a 22 bit address space compared
to the UNIBUS' 18 bit space, which means that mapping from bus space to
real memory is easier with a Q-bus. Peripherals are also cheaper on a
Q-bus. There is no reason to use a UNIBUS over a Q-bus.
The CI bus is meant to be a communications channel between processors.
It talks a magic protocol and runs at 70 meg. The cost of a CI
controller (~$20k) is more than the base microVAX II configuration. It
doesn't make a lot of sense to spend more money on the CI controller
than on the computer system.
I don't know what the microVAX III will be like, and I don't think that
DEC does either. Yes, there are several VAXen in the works (there always
are), and at least one has to be microprocessor based, but as far as
something close enough to being a product to be called a microVAX III? I
doubt it.
----------------
Marty Sasaki net: sasaki@harvard.{arpa,uucp}
Havard University Science Center phone: 617-495-1270
One Oxford Street
Cambridge, MA 02138info-vax@ucbvax.ARPA (06/05/85)
From: rna!dan@nyu-cmcl2 (Dan Ts'o) > I find the rumors about things truly amazing, especially the microVAX > III. A recent note mentioned that the next microVAX will not have a > Q-bus, but might use a CI or a UNIBUS. This is very unlikely. > The Q-bus is a pretty fast bus, almost twice as fast as a UNIBUS in I have heard enough rumors about the uVAX III to believe its more than fantasy. Much of the industry speculates that the uvax III will be the introduction of the new BI bus, a DEC 32bit bus designed to compete with VME and Multibus II. A year or two ago the Multibus I, Qbus each shared about 30% of the market. Since then, VME has really grown while the Qbus has shrunk. DEC really needs a better bus to compete. The Qbus is not a pretty fast bus. Most SMD controllers on the Qbus still need to do sector interleave (as much as 3:1) to slow down the transfer rate onto the Qbus. True, the new block mode DMA protocol and the PMI for the uvax II help somewhat. But the Qbus is plain slow when compared with VME or Multibus II. So the uvax III may well be the 78032 chip set on the BI bus. The chip is sure plenty fast. The I/O bus need help. There is also supposed to be yet another VAX chip set in the works, a multichip set so called VLSI VAX which has somewhat better performance than the 78032 of the uvax II. Anyone know anything about it ? Cheers, Dan Ts'o Dept. Neurobiology Rockefeller Univ. 1230 York Ave. NY, NY 10021 212-570-7671 ...cmcl2!rna!dan
info-vax@ucbvax.ARPA (06/05/85)
From: decwrl!decvax!ittvax!keegane@BERKELEY (Edward Keegan) MicroVAX III prototypes do exist. How far away they are from "productizing" remains a different issue. Ask your DEC rep about code name SCORPION and watch his response.