Jon,

Coming from more of a user integrator person here...
I think that I am with you on liking option 3 the best with number 2
next in line. I would even go so far as marking the 'old' driver as
deprecated and slated for removal on the next release. That warns
everyone that if they want to run the next release they need to get with
the game or they will have to be content with this being the last
release that supports their hardware. I don't like option number 1. It
just begs for a high number of bugs to be introduced that could effect
both camps of users.

My big questions...
- Do we know when this changed occurred to actual products in the
marketplace?

- Are there still cards being sold that ONLY conform to the old behavior
of needing the direction changed?

In your first email you asked, "Are all the parport chips that
NEED the "manual" direction changing so far back in history
that nobody could ever run a current LinuxCNC on those
motherboards and parport cards?" My response is that even if they could
run a current LCNC release on them, if they are 15 years old anyway
perhaps the question should not be if they could, but if they should.

I also see this as making a large number of cards available for use. I
hate having to dig for a source of one specific item that may not even
still be in production. If I have a card die in an old system, I would
much rather be able to look for one of many options to replace it in
exchange for being stuck on an older software release so I can keep
using my antiquated hardware.

I am of the opinion that if legacy machines are working... leave them
alone! If it makes parts reliably everyday, why do you want to be
messing with newer versions of LCNC. If a parport card dies on a 15 year
old system, you should probably look at upgrading the whole computer as
other items might not be far behind. In that case, move up to a newer
version of LCNC while you are at it.

Significantly increasing your development workload just so that a
relatively few users can run ancient hardware in combination with a new
release is not worth it in my opinion. Having an expectation that users
upgrade their hardware once a decade in order to be able to run the
latest software release is perfectly acceptable. Heck, 5 years should be
acceptable. If you wanted to run the latest software (not to be confused
with maintaining your current software) from any of the proprietary
control system companies on 15 year old hardware they would laugh at you.

Just my thoughts.


On 02/26/2017 11:37 AM, Jon Elson wrote:
> On 02/25/2017 01:29 PM, Jon Elson wrote:
>> Over the years, it has been seen that certain parallel port
>> chips did not work properly with my hal_ppmc driver.
>>
> Hmmm, I was hoping to get more discussion of this.  It 
> concerns a MAJOR overhaul of my hal_ppmc driver.
> 
> I can see 3 ways to deal with the problem:
> 
> 1.  Make it automatic, it tries with the "manual" port 
> direction change off, if no boards can be sensed, turn the 
> direction change on, and try again.
> 
> 2.  Make it a command line option.
> 
> 3.  Make two versions, hal_ppmc and hal_ppmc_old.  Chack 
> after a year and see if anyone is actually using 
> hal_ppmc_old, and if not, remove it from LinuxCNC.
> 
> I kind of like option 3, as it will have a lot cleaner code, 
> and also, if it turns out to be a big mistake, we just 
> remove the new version instead.
> 
> One additional concern would be the multi-port option of 
> hal_ppmc. As far as I know, NO ONE has EVER used this 
> feature, but it does allow you to have up to 3 parallel 
> ports in use on the same system. How do you handle it if one 
> requires the manual direction change, and one doesn't?  Ugh, 
> I really don't want to spend days hacking on code that will 
> never be used.
> 
> Sorry my original message was so long, I wanted to set the 
> stage for the question.
> 
> Any comments?
> 
> Thanks,
> 
> Jon
> 
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