BRL-CAD on VAX README
=====================

One of the first systems to run BRL-CAD was the VAX.  In particular, a
VAX 11/780 named VGR is the baseline reference machine for the BRL-CAD
Benchmark suite.  Through the 80's and most of the 90's, BRL-CAD was
compiled for and maintained on VGR running 4.3 BSD until the hardware
was finally decommissioned.

BRL-CAD has been successfuly compiled for and run under the simh
Computer History Simulation Project's VAX simulator.  Using this
simulator, it's feasible to install one of the BSD variants
(e.g. NetBSD) and using the GCC compiler, obtain a compilation of
BRL-CAD with minimal effort.  As of the last effort involved in
compiling BRL-CAD under this environment, there were a few steps
necessary that include the following:

  - Define the preprocessor symbol "vax"
	./configure CPPFLAGS=-Dvax

  - Disable compilation of libfft and sig.  The FFT library builds
    convolution kernels that are too large for the usual VAX memory
    sizes.
	edit src/Makefile.am and remove libfft and sig lines

  - Compile against libm.a instead of libm.so.  The shared object
    library (at least under NetBSD) is buggy and will cause run-time
    bus errors (i.e. rt will crash).
	make LIBM=/usr/lib/libm.a

After those steps, you should at least be able to perform a benchmark
compilation (i.e. "make benchmark"), raytrace images, and obtain
performance metrics.
