DIY CNC

Things a machine can physically do are absolutely the same for parallel port and Mesa card, so there are no limitations either way.
Things that are the same:
-you can make whatever you, your CAM, and your machine can do
-any machine, 3, 4, 5 or more axis, robot, lathe all will work
-you can use more than one of any of those, and you can combine them as you need.
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Things that are not the same:
-pulse speed and subsequently the machine speed
-Parallel port can do approx. 20000-50000 pulses or encoder reads per second
-Mesa can do over 1000000 (1 million, some even 10 million) pulses per second
-Parallel port can have 12 outputs and 5 inputs in OUT mode, 4 outputs and 13 inputs in IN mode, 8 outputs and 9 inputs in mode X. Not all ports can do this, but all built in ones do.
-Mesa can have any of the 34 pins (some cards have more IO) set as input or output in hal, granted it is not used as Stepgen or PWM or encoder or sserial.
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Or in short, parallel port with LinuxCNC will be enough for any hobby machine and most 24/7 use machines, even for some industrial machines that are not to complex
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Yes, i do have a lot of Mesa boards/machines (probably over 70 or 80 or more), and yes i still use parallel ports and still have machines in daily use with both for over 15 years (i am fuzzy on the exact numbers and timelines)

rodw wrote:

... but thread milling solves the thread cutting dilema on all machines and is much easier on small machines.

Those things are magnificent and make tapping possible on low torque/power spindles.