oyej@vax5.CIT.CORNELL.EDU (05/31/89)
I am looking for information as to why the micro VAX I is unpopular. I believe that a major hardware design flaw is the reason that one doesn't hear about it anymore. I am thinking of trading in a PDP 11/23 for a micro VAX I. Any words of advice? Ken. oyej@vax5.cit.cornell.edu
bcw@rti.UUCP (Bruce Wright) (05/31/89)
In article <18702@vax5.CIT.CORNELL.EDU>, oyej@vax5.CIT.CORNELL.EDU writes: > I am looking for information as to why the micro VAX I is unpopular. > I believe that a major hardware design flaw is the reason that one doesn't > hear about it anymore. I haven't heard of any major hardware design flaws in the MicroVAX I unless you count being S-L-O-W as being a flaw ... > I am thinking of trading in a PDP 11/23 for a micro VAX I. > Any words of advice? You might not find the MicroVAX I much faster than a 23 except that, of course, the software can have more buffering and room to be more intelligent (which means fewer disk I/O operations) - for some applications this can be quite significant (even the dominant factor) even though the basic CPU isn't really tremendously faster. Of course, if you are doing 32-bit arithmetic the MicroVAX I does better than the 23 (not that that's so hard when the 23 doesn't have 32 bit instructions). Any MicroVAX I's out there are also likely to be sold with small amounts of memory and small, slow disk drives. If you can afford it, and don't mind the proprietary hardware setup, you may do better to try to locate a used MicroVAX 2000. These are machines based on the MicroVAX II chipset, but with a proprietary architecture that you can't plug standard QBUS devices into. DEC does sell a few things for it at only slightly outrageous prices, if you're lucky you might be able to get one that's reasonably configured without having to go to DEC at all. It's only slightly slower than a standard MicroVAX II. Bruce C. Wright
cdl@mplvax.EDU (Carl Lowenstein) (06/02/89)
In article <18702@vax5.CIT.CORNELL.EDU> oyej@vax5.CIT.CORNELL.EDU writes: >I am looking for information as to why the micro VAX I is unpopular. >I believe that a major hardware design flaw is the reason that one doesn't >hear about it anymore. The MV1 does not have hardware for address mapping between DMA peripherals and memory. It would be a good trick to do so, since there is only one Qbus for everything. Storage which appears to a program as contiguous space (virtual addresses) need not be at contiguous physical addresses in the Vax architecture. This greatly complicates transfer to and from mass storage devices such as disks and tapes when there is no hardware help. Probably that is the design flaw. -- carl lowenstein marine physical lab u.c. san diego {decvax|ucbvax} !ucsd!mplvax!cdl cdl@mplvax.ucsd.edu
cmr@m2-net.UUCP (Chuck Rader) (06/06/89)
The MicroVAX I doesn't implement the full VAX instruction set, so it relies on software emulation of some instructions. This, combined with slower clock speed makes it a lot slower than other MicroVAXen. It also was originally released with a different version of VMS. -- Chuck Rader, Manager, Computer Technical Services, University of Detroit voice: 313-927-1349 I don't worry 'bout a thing 'cause fax: 313-927-1011 I know nuthin's gonna be all right e-mail: cmr@m-net.ann-arbor.mi.us
WTR@ceres.physics.uiowa.edu (SYSWTR@IOWASP.PHYSICS.UIOWA.EDU) (06/13/89)
One might want to look and see how well the UV-I is supported under the lates VMS release. I suspect that it is difficult to put VMS on the drives that are available on the UV-I (too small). In addition, the UV-I is limited to 4MB of memory (I have a uV-II with 5 Mb that could stand another 4Mb) Bill Robison