Still lots of people using parallel port from the control computer although there are things you need to watch if you go down that road, computers haven't come with a parallel port connection for quite some time now although some motherboards still have the header so you can plug in a ribbon cable & you could also fit a PCi parallel port, when I first rebuilt my machine I had a parallel port connection to a 4 axis breakout board. Probably not what I would suggest if someone were to ask me how to connect to a control computer but it is a method that seems to still get used
Things have moved on & now there are a lot more people connecting via either USB or Ethernet, both work very well, prices have come down a lot from a few years ago but it is still a more expensive way to connect.
When I upgraded from the old parallel port connection I opted for Ethernet, just personal choice really for my machine & what I do either would have done me just fine.
I have a UC400ETH motion controller which is connected to a gigabyte (I think) PCI express network card in the control computer
The UC400 is connected to a basic breakout board, can't honestly remember the make. 4 axis of which I just use X,Y & Z. Gantry on my machine is very low so a 4th axis is not an option without some major surgery. The BOB has 2 relay outputs, one is used for the spindle the other is just spare at the moment.
5 inputs on the BOB but they aren't all used, one for emergency stop, one for the X, Y & Z homing switches which are wired in series & one for the touch plate although that isn't working just now, think I have a break in the wire somewhere. Just haven't got round to fixing it yet.
As I said in previous post I have 3 AM882 drivers for the stepper motors. X & Y axis are a single Nema34 & Z is a nema23. The original slo-syn steppers were past their sell by date when I got the machine, I had some nema23 motors that I was going to use but that would have meant making new mounts plus a lot of messing about cutting holes as the original motors sat in quite a tight space & the nema23's body was longer. So I just bought a couple of nema34's that fitted straight in
The machine originally ran on about 30V DC but you have to remember that this machine is over 30 years old & things have changed a lot since then, the original transformer is about the size of a garden shed
OK exaggerating a bit there but you get the idea