On 03/30/2020 07:17 PM, John Dammeyer wrote:
On 03/30/2020 04:27 PM, John Dammeyer wrote:
When did the hal come in? This stuff has dates on or around 2004--2007.
John Kasunich proposed HAL at a meeting in 2005, I'm pretty
sure, and demonstrated a
small version of it in 2006, I think. It was merged into
EMC some time after that, probably
late 2006 to 2007.
Jon
Thanks Jon,
For some reason I thought it was a lot earlier.
A major roadblock had developed in adding new things to EMC
about 2002 or so.
There was no way to have axes slave to the spindle, for
instance. Since all of EMC
was just a few massive chunks of code, making any but the
most trivial change in
the real time side was a HUGE hassle. I know -- for my
boards, i needed to move
the auxiliary I/O (spindle, coolant etc.) over to the real
time side, as everything communicating
with my boards needed to be coordinated through a single
thread. It took mods to
about a dozen different files to get it done.
Some of us developers felt that breaking out many of these
components into smaller
pieces that communicated through some sort of switchboard
that was easily adjusted
would be a big improvement. Some developers thought this
would overly complicate
EMC and cause performance issues. This was back when EMC
was still run on Pentium
Classic computers.
John Kasunich set to work and produced a very elegant code
which did add some
complexity, but had almost ZERO performance impact -- all
data was passed
with pointers, so no extra overhead when running. And, it
did make it MUCH easier
to add components to do special stuff. Most of the
developers thought it was great,
and a solution to many issues that were just too difficult
to deal with.
The logjam was broken, and a whole bunch of new features and
capabilities were
realized.
Jon
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