Mach3 on Win 7 32 bit with parallel port.

All had been working OK other than an occasional drift on the Z axis which I was about to track down the cause of when events meant I had to put it all to one side to pick up at a later date. The date arrived, and a whole bunch of Win 7 updates got installed, including the Spectre / Meltdown patch.  I did the registry change to get MACH3 working again.

I am now have still an issue with jog step, all axes behaving the same.  The step, for testing, is set to 1mm.  When I try it the MACH DRO shows the correct movement the stepper just makes noises but doesn't actually move.  I could well imagine the direction signal is whipping up and down.

Is there a known issue with other Windows updates hat could cause this? Could something have got corrupted on the MACH3 config ( it looks OK), or is there likely a hardware fault?

-CS

Let me add to this. As far as i can tell, other than this, the machine is running normally.  It's quite possible the jog step has always behaved as described above and I'd simply never tried it.

I found another oddity that may or may not be related.  To debug the original Z axis issue I disabled the X and y axes and ran the G code that causes the Z error.  The program runs for a while and then has a long unexpected pause.  If I re-enable one of X or Y I see that mach3 is positioning the tool far outside where it should and it then follows a sort of sinusoidal pattern going to and for a minute or so. Try again with all axes enabled and it works.  Clearly something is far wrong with mach here.

I found out a couple of things.

The jog step issue is failing as the default feed rate was 6mm/min.  The set feed rate command was missing from the initialisation string in general config. It remains a question as to why a slow feed rate doesn't work, but at least I have a practical workaround.

The odd behavior when X and/or Y axis are inhibited is a bug in mach3 for sure.  It happens when executing a G2/ G3 draw arc incremental command.  It would seem the inhibited axis causes mach3's calculation to go off the rails. The easy solution is just to unplug the cable(s) to the motor.