RS6000 an GL programmer's perspective

[randy frank]

This is in general reply to Matt Machlis' questions about the
IBM RS/6000.  (the machine was a 3xx? 16Meg ram)
	I had a demo machine for about 3 weeks earlier this year.
I ported about 15 applications to it and demoed it at our site.
The apps were all IRIS GL code, mostly scientific FORTRAN and 
included p3d, NCSA HCVIS, NCSA HDF, FRODO, TGIF, some radiation planning
software, a solids modeller, and basic image and 3d object display/
manipulation software and a GL based 128k Apple //e emulator.
 (the latter few being locally developed 
workspace applications.)
	Porting was fairly simple especially for our sw as it had been
written using only base GL calls which could be isolated and have libs
written around them for porting to other platforms.  IE we plan to port
as we code, including graphics. 
	Graphically the speed was about the same as our 4D20.  A noted
exception is that the mapcolor routine was INCREDIBLY SLOW!!!. Also the
implementation of popup menus left a LOT to be desired.  A last graphics
note, I was unable to get any of my rectread based software to work.  IE
I could NOT reliably read an image from the buffer.  Most of the stuff
I saw will probably be corrected in a future OS release.  Basically it's
a 4D20 graphically.
	The CPU was quick.  Probably in the R3000 25Mhz range especially
in floating point.  If your code is integer only the machine was not 
much faster than a 4D25.  The floating point stuff was difficult to
measure as its performance was wildly erratic.  Some stuff ran very fast
but as the numbers got small (iterative fitting) it slowed down.  I found
the OS to be fairly stable for a prerelease and I liked their system
administration tool (SMIT) very much.
	In a nutshell the machine was a 4D20-25 that was a little erratic.
Its UNIX takes a little getting used to but is ok.  I would like to see
another release of the OS before I bought one (unless the discount were
over 60%).  Lots of potential...
Note: Many of the ports were deleted and I don't know if I could provide
the source to the port although I could provide hints.  My porting 
success rate was about 80% in two weeks.  I believe 90-95% could be
ported.

--
rjf.
Randy Frank, Engineer                       |  (319) 335-6712       
University of Iowa, Image Analysis Facility |  73 EMRB              
randy at tessa.iaf.uiowa.edu                   |  Iowa City, IA 52242