cbs@cad.cs.cmu.edu (Clauss Strauch) (08/28/90)
We are thinking of getting some DECstation 5000 PXG and/or PXG
Turbo machines. I'm interested in hearing any positive/negative experiences
that folks may have had with them.
I also have two specific questions:
-- What sort of software is currently out there to take advantage
of the hardware?
-- What are the advantages(besides speed) of getting a PXG with
the optional Z buffer, vs. a PXG Turbo?
Thanks in advance!
-- Clauss Strauch
Engineering Design Research Center, CMU
cbs@cs.cmu.edu
...!harvard!cs.cmu.edu!cbsallen@basalt.uucp (Allen Akin) (08/30/90)
In article <10338@pt.cs.cmu.edu> cbs@cad.cs.cmu.edu (Clauss Strauch) writes: > > [...] > -- What are the advantages(besides speed) of getting a PXG with > the optional Z buffer, vs. a PXG Turbo? Functionally, a 24-plane PXG is identical to a PXG Turbo. Only the performance differs. In a nutshell, the PXG has: 40MHz i860 for geometry acceleration One 5x1 array of pixel engines running at 80ns Two image buffers (8 or 24 planes each) 240ns random access time, 80ns page-mode access time Optional Z-buffer (always 24 planes) 240ns random access time, 80ns page-mode access time The PXG Turbo has: 44MHz i860 for geometry acceleration Two 5x1 arrays of pixel engines running at 60ns Three image buffers of 24 planes each 180ns random access time, 60ns page-mode access time Z-buffer with 24 planes 180ns random access time, 60ns page-mode access time The Turbo offers about 10% improvement over the standard PXG in geometry acceleration, about 160% improvement for large-area pixel fills and aligned pixel copies, about 100% improvement for polygon rasterization, and about 35% improvement for vector rasterization. The extra 24 planes of image buffer are useful for storing images for fast access -- for panning, antialiased image accumulation, background data for cartography, additional drawing layer for MCAD, etc. Followups to comp.sys.dec. Allen