grr@cbmvax.UUCP (George Robbins) (11/28/89)
Uh... If I have a color VAXstation 3100 and a monochrome DECstation 3100,
can I somehow swap the display controller components and get me a color
PMAX and and monochrome PVAX? Monochrome at this kind of low resolution
is such a sad joke in this day and age...
--
George Robbins - now working for, uucp: {uunet|pyramid|rutgers}!cbmvax!grr
but no way officially representing arpa: cbmvax!grr@uunet.uu.net
Commodore, Engineering Department fone: 215-431-9255 (only by moonlite)rwood@dec.com (Richard Wood) (11/29/89)
In article <8732@cbmvax.UUCP>, grr@cbmvax.UUCP (George Robbins) writes: > Uh... If I have a color VAXstation 3100 and a monochrome DECstation 3100, > can I somehow swap the display controller components and get me a color > PMAX and and monochrome PVAX? Monochrome at this kind of low resolution > is such a sad joke in this day and age... No. The two designs were completely independent. *UNIX is a registered trademark of AT&T in the U.S. and other countries. -- --------------------------------------------------------------------- Richard Wood Corporate Worksystems Team Digital Equipment Corp. ========================================================================
abstine@image.soe.clarkson.edu (Arthur Stine) (11/29/89)
From article <8732@cbmvax.UUCP>, by grr@cbmvax.UUCP (George Robbins): > Uh... If I have a color VAXstation 3100 and a monochrome DECstation 3100, > can I somehow swap the display controller components and get me a color > PMAX and and monochrome PVAX? Monochrome at this kind of low resolution > is such a sad joke in this day and age... > Uh... no... the PMAX and PVAX use a completely different frame buffer, the pVAXes (color) being a GPX processor and the PMAX being a dumb color or monochrome frame buffer driven by the CPU. I don't think DEC has an upgrade option for the PMAX to upgrade from mono to color even. -- Art Stine Sr Network Engineer Clarkson U ABStine@CLVMS.Clarkson.Edu
envbvs@epb2.lbl.gov (Brian V. Smith) (11/29/89)
In article <1989Nov28.191803.18970@sun.soe.clarkson.edu>, abstine@image.soe.clarkson.edu (Arthur Stine) writes: < From article <8732@cbmvax.UUCP>, by grr@cbmvax.UUCP (George Robbins): < > Uh... If I have a color VAXstation 3100 and a monochrome DECstation 3100, < > can I somehow swap the display controller components and get me a color < > PMAX and and monochrome PVAX? Monochrome at this kind of low resolution < > is such a sad joke in this day and age... < > < Uh... no... the PMAX and PVAX use a completely different frame buffer, the < pVAXes (color) being a GPX processor and the PMAX being a dumb color or < monochrome frame buffer driven by the CPU. I don't think DEC has an upgrade < option for the PMAX to upgrade from mono to color even. What were the reasons for not using the GPX processor in the DS3100? To go to a dumb frame buffer driven by the CPU seems like a giant step backward. _____________________________________ Brian V. Smith (bvsmith@lbl.gov) Lawrence Berkeley Laboratory I don't speak for LBL, these non-opinions are all mine.
grunwald@foobar.colorado.edu (Dirk Grunwald) (11/30/89)
this was hashed out in comp.arch a while back. DEC claims that the CPU is memory bandwidth limited anyway, and that a GPX-like processor wouldn't buy them anything. It's also cheaper to not have a GPX processor. For B/W performance, I'd agree. I don't know how the colorad DS3100's perform. Dirk Grunwald -- Univ. of Colorado at Boulder (grunwald@foobar.colorado.edu) (grunwald@boulder.colorado.edu)
eric@batcomputer.tn.cornell.edu (Eric Fielding) (11/30/89)
In a recent article envbvs@epb2.lbl.gov (Brian V. Smith) wrote: >What were the reasons for not using the GPX processor in the DS3100? >To go to a dumb frame buffer driven by the CPU seems like a giant step >backward. >Brian V. Smith (bvsmith@lbl.gov) I can't comment on DEC's reasoning, but the people in the department next door told me that the DS3100 seems to outperform the VAXstation 3540 at some graphics tasks. Especially since there is no documented way to access the special graphics processors in the 3540. It would also seem like it would agree with the 'RISC' philosophy to avoid putting complex operations into hardware or firmware. ++Eric Fielding eric@geology.tn.cornell.edu
neideck@kaputt.dec.com (Burkhard Neidecker-Lutz) (11/30/89)
Brian V. Smith writes: >>> What were the reasons for not using the GPX processor in the DS3100? >>> To go to a dumb frame buffer driven by the CPU seems like a giant step >>> backward. One reason was that it was cheaper and faster to develop this way and the other (mayor) reason is that this actually is 2-4 times *faster* than using the GPX chip set. For monochrome the choice was clear, we weren't so sure about the color case at first. Turns out that with the sole exception of scrolling the dumb frame buffer with CPU is faster than the GPX hardware by large amounts. Take a look at a DECstation 3100 running UWS2.1 (or 2.2...). Burkhard Neidecker-Lutz
mikem+@andrew.cmu.edu (Michael Meyer) (11/30/89)
The color decstation performs about as fast as the balck and white version. That is truely remarkable (and good). --Mike Meyer Statistics, CMU
rwood@vajra.dec.com (Richard Wood) (11/30/89)
In article <4305@helios.ee.lbl.gov>, envbvs@epb2.lbl.gov (Brian V. Smith) writes: > What were the reasons for not using the GPX processor in the DS3100? > To go to a dumb frame buffer driven by the CPU seems like a giant step > backward. The graphics performance of the DS3100 is substantially faster than the GPX subsystem would allow, even without an accelerator. While the GPX subsystem would have reduced the CPU load somewhat, it also would have forced an upper limit on the graphics performance of the machine. Considering that adding in the additional subsystem would take additional time, increase cost and complexity - all without adding substantial performance gains - it became obvious that the solution was a dumb frame buffer. The philosophy was "we got this extremely high powered chip in the middle of this design, let's make it work for a living." Thus the elimination of DMA and graphics accelerators made the system much simpler to design, less expensive, and much more reliable when complete. -- --------------------------------------------------------------------- Richard Wood Corporate Worksystems Team Digital Equipment Corp. ========================================================================
jg@max.crl.dec.com (Jim Gettys) (12/05/89)
Sorry, the DECstation and VAXstation use completely differet display hardware; you can't mix and match anything but the monitors (which are shared in common between the machines. Jim Gettys Digital Equipment Corporation Cambridge Research Laboratory
jg@max.crl.dec.com (Jim Gettys) (12/06/89)
The GPX on the PMAX would have been a "graphics decellerator". For example, at best, the GPX can do around 20k characters/second. PMAX does around 50-60K characters/second (in color, monochrome is yet faster; R4 numbers are around 100k for color). Similar numbers apply for almost all graphics operations, with the exception of aligned raster-op, where memory bandwidth on the PMAX is less than that available on the GPX. The unaligned case, which one might have expected the hardware to help on, turns out to be slower in hardware than the PMAX does in software. Everything else is much faster. On the whole, for most applications, the PMAX outperforms a GPX system by a large margin. For complex stuff, a large multiple indeed. So go look at real numbers before coming to any conclusions on graphics performance. The x11perf program will give you an interesting set of performance numbers to work from. - Jim Gettys