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parallel port
« on: June 13, 2009, 05:46:43 PM »
Can anyone explain in more detial what's going on to keep the parellel port pulse frequency bouncing all over the place?

I'm a PC guy, and I'm pretty sure I can figure out what's really going on and the
official terms I can Google and findout more about what's going on.

What exactly is the pusle frequency?

Is it the number of free cycles on  main bus?

Why does mouse movement boost the speed back up?

Do PCI/AGP video cards and the like take up bandwidth? Aren't they on a separate AGP port?

I'm hoping to build a new box that will have better performance, but I want to understand what performance exactly
I'm trying to build for.

Any links or info is greatly appreciated.


Re: parallel port
« Reply #1 on: June 13, 2009, 08:22:17 PM »
The step pulses are generated by software, in a very low-level driver.  Anything in the system that loads the CPU, or the memory busses, can prevent that driver from issuing the pulses exactly when it should.  Video drivers, network drivers, and other high-bandwidth devices can do this.  On-board graphics controllers can be particularly bad, since they generally keep the frame buffer in main memory, so can significanrly increase latency of CPU accesses to memory.  Get the Windows optimization instructions from the Artsoft website.  That will give you a good idea the kinds of things that can affect pulse stability.

Ray L.
Ray L.

Offline Chip

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Re: parallel port
« Reply #2 on: June 13, 2009, 10:23:34 PM »
Hi, Eric

Hears the set file, It has a large view screen, The pop out Pendent is for a Lathe, Just a work in progress .set file to look at.

« Last Edit: June 13, 2009, 10:33:38 PM by Chip »

Offline Jeff_Birt

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Re: parallel port
« Reply #3 on: June 14, 2009, 12:35:06 AM »
At the risk of going into broken record mode - I really hate seeing folks spend a lot of time trying to make their machine play nice with the LPT driver. In general you need to shut off all the power saving options and not install anything but Mach on your PC. If your using a slower machine with shared video memory you can have problems as the video process will tie up the memory bus. There are many, many PCs that work just fine but some folks just have bad luck.

I'm sold on using the SmoothStepper now: http://soigeneris.com/Warp9.aspx , as it just works. No more fussing with the LPT.
Happy machining , Jeff Birt