stepper motors glitching

[mel_earp]

Robins explanation is fine as a basic understanding, but as in any field it can and does go much deeper than this. I am sure that Robin is using the term "time slicing" in an informal manner, but the original time slicing based operating systems used fixed and then variable time slices which could not be interrupted. This is no longer true for Windows and it doesn't time slice in the strict meaning of the term. Also made more complicated with the advent of multi-processor chips. But Windows doesn't, and this is the problem, have much in the way of mechanisms to guarantee that processes that need it, get the resources in a timely manner. This is what I meant when I said that Windows is not a real time operating system, and it is never likely to be so because, apart from it being too hard, there is no commercial reason why Microsoft should make it so.

A real time operating system would know that certain Mach processes were time critical and would do all that is possible to give them the resources as soon as they needed them. Windows makes a bad job of this. The time taken to do this is called latency and this is one of the things the Mach (and EMC) test programs try to measure.

EMC will generally be better at this because it is based on a version of Linux with real time extensions - not fully real time from the ground up, but not bad.

If the source of this problem is the software (not yet proven) then the only hope is as Robin says, kill everything that is not essential for Mach. That includes AVG, any additional hardware drivers... I think it unlikely that a network driver could cause this, but it is known that some network drivers can spend time looking for an UNPLUGGED cable. So if you have a network driver try both situations, with the cable being plugged in as the preferred option. The best way would be a clean Windows install. Some software packages are notorious for not quite uninstalling themselves. So, if you have installed anything else and uninstalled it, you have to consider a Windows clean install and clean means ask for the disk to be formatted along the way. A Windows install over an existing copy won't necessarily get rid of the rubbish. The install process might just pick up stuff from the old installation.

(BTW - I used to design real time software)

[irving2008]

(BTW - I used to design real time software)

You and me both :)

Of course there are true real-time extensions for Windows, as well as the embedded Windows with RTX, but the licencing costs of those makes it unlikely to get into hobby-level software. There was an OpenSource RTX sometime back, but it seems to have died off....