[burdickjp]

I've found a few motherboards which offer parallel ports. They're small, with cheap hardware.

Like these, which have almost the exact same hardware:
http://www.newegg.com/Product/Produc...82E16813157498
BIOSTAR J1800NP Intel Celeron J1800 2.41GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
Open Box: ASUS J1800I-A Intel Celeron Dual-Core J1800 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com

Or these, which are a bit different:
ASRock AD2550B-ITX Intel Dual-Core Atom D2550 1.86 GHz Intel NM10 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
GIGABYTE GA-E2100N AMD E1-2100 APU 1.0GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
http://www.newegg.com/Product/Produc...82E16813157565

They're all fanless, which keeps the crap out. I've got an appropriate enclosure. I actually think it's the same enclosure Tormach uses. Could use a solid state drive.
These should have enough power, but I'm curious what else I should be looking for in a dedicated LinuxCNC system.

[PCW_MESA]

I've found a few motherboards which offer parallel ports. They're small, with cheap hardware.

Like these, which have almost the exact same hardware:
ASRock D1800B-ITX Intel Celeron J1800 2.41 GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
BIOSTAR J1800NP Intel Celeron J1800 2.41GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
Open Box: ASUS J1800I-A Intel Celeron Dual-Core J1800 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com

Or these, which are a bit different:
ASRock AD2550B-ITX Intel Dual-Core Atom D2550 1.86 GHz Intel NM10 Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
GIGABYTE GA-E2100N AMD E1-2100 APU 1.0GHz Mini ITX Motherboard/CPU/VGA Combo - Newegg.com
http://www.newegg.com/Product/Produc...82E16813157565

They're all fanless, which keeps the crap out. I've got an appropriate enclosure. I actually think it's the same enclosure Tormach uses. Could use a solid state drive.
These should have enough power, but I'm curious what else I should be looking for in a dedicated LinuxCNC system.

There are actually many J1800/J1900 motherboards that have parallel ports but some just have a header rather than a DB25 connector so may require an adapter cable

Note that these are quite a bit faster than the Atom D25XX series (as is the last MB link which is a AMD)
These are all fanless and have a LPT port on the motherboard: (you can always add a PCI pr PCIE parallel port to other motherboards as well)

http://www.newegg.com/Product/Produc...82E16813157494
http://www.newegg.com/Product/Produc...82E16813157497
http://www.newegg.com/Product/Produc...82E16813157513
http://www.newegg.com/Product/Produc...82E16813157495
http://www.newegg.com/Product/Produc...82E16813128688
http://www.newegg.com/Product/Produc...82E16813157546
http://www.newegg.com/Product/Produc...82E16813157565
http://www.newegg.com/Product/Produc...82E16813138412

[burdickjp]

Is there any advantage to an onboard parallel port, versus using one of the many PCIe cards designed for CNC control?
Cost is obviously an advantage of just using the parallel port.

[PCW_MESA]

Is there any advantage to an onboard parallel port, versus using one of the many PCIe cards designed for CNC control?
Cost is obviously an advantage of just using the parallel port.

Yeah lower cost and perhaps lower profile are advantages of onboard ports. they also are at known addresses so
less fiddly to set up than plug-in PCI/PCIe parallel ports.

If you mean a purpose built CNC oriented plug in card vs a parallel ports thats a whole different kettle of fish

[burdickjp]

If you mean a purpose built CNC oriented plug in card vs a parallel ports thats a whole different kettle of fish

How about we limit the comparison to things using the parallel port connector, such as the Mesa 6I25 board: Mesa Electronics
What would be the advantage of the Mesa board over using a system with a parallel port?

[PCW_MESA]

Something like the FPGA based 6I25 allows higher step rates (to 8 MHz in the 6I25 case) and lower jitter that the
parallel ports software generated steps, usually improving smoothness and top useful rapids speed.

The 6I25 can also count high resolution incremental and absolute encoders (SSI,BISS and Fanuc), generate
high resolution PWM, and has SPI and serial options as well for I/O expansion.

[burdickjp]

Something like the FPGA based 6I25 allows higher step rates (to 8 MHz in the 6I25 case) and lower jitter that the
parallel ports software generated steps, usually improving smoothness and top useful rapids speed.

The 6I25 can also count high resolution incremental and absolute encoders (SSI,BISS and Fanuc), generate
high resolution PWM, and has SPI and serial options as well for I/O expansion.

That's a fantastic answer. Thank you very much.

[NMay]

PCW-MESA do you have any experience with any of the boards you listed with the 6I25 card? Any hiccups to be aware of?

Sorry to raise a necro thread.... looking at building a new controller.

[wendtmk]

PCW-MESA do you have any experience with any of the boards you listed with the 6I25 card? Any hiccups to be aware of?

Sorry to raise a necro thread.... looking at building a new controller.

I would hope he has some experience with the boards. He's the one who makes them.

[PCW_MESA]

Compatibility problems are pretty rare with the 6I25, mostly older MBs with X16 PCIE slots that dont implement X1 properly
I would expect all J1800/J1900 MBs to just work