Recommendation for Upgrading an Original parallel port KX1 to USB or Ethernet

[JimG]

That's a bit rubbish if you can't use a step/dir output to control a spindle.

Other options to look at that would be a direct plugin to a parallel port, would be the CNCDrive UC100, or the PMDX-411 (which is Mach 4 only).
If you're wanting to rewire and do away with the parallel port, there are a lot of other options.

I'm not too keen to do a re-wire and using the existing parallel port would be my preference. When I got the KX1, the information about the machine's electronic guts was pretty well non-existant - a block diagram of the inter-component wiring being the sum total. So I'm reluctant to delve further into that in case it just raises more problems.

I've looked at the UC100 and also the Warp9 ESS. I've researched both as much as I can and I might plump for the ESS since that appears to have a lot more documentation about interfacing with Mach3. I'm quite happy with Mach3 since the majority of my work is fairly straightforward 2.5D work out of Cut2D and Mach3 has given me no problems with that, so upgrading to Mach4 is an expense I would hope to avoid. The late John Stevenson also ran a support forum for the Seig CNC mills and I think I remember the Smoothstepper being discussed as a suitable upgrade, although the forum has now gone so I can't refer back to it.

Jim