Advice for choosing a compatible PC

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31 Aug 2023 00:51 #279428 by tommylight
You already have:
-several PC's with parallel ports
-stepper drives and motors on the machine
So, you can download the wheezy ISO from the downloads page, write it to USB, boot the PC's from it and see what latency you get.
Then, take out the "usb mach3 bla bla" and wire the PC parallel port directly to drive inputs, power on the machine, start LinuxCNC and play a bit, see how it turns out.
You already have everything.
At any time later you can get a Mesa 7i96S or if they become available, any of 5i25 or 6i25 or 7i92.
The first is a full controller with screw terminals n'stuff, the last 3 are the same thing but for PCI, PCI-E or Ethernet and have no screw terminals and are same as 2 parallel port but with much, much faster step rates.
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31 Aug 2023 03:27 #279439 by rodw
For a stepper based machine look for a mesa 7i96s.
It operates at up to 10 Mhz bu that is faster than required....

What happens with a mesa board is the stepgens are commanded by Linuxcnc to run at a specific frequency which it will do forever unless told to change the Frequency.

Linuxcnc can command the frequency to be changed 1000 times a second. Having the step generation offloaded to dumb external hardware takes a lot of load off the computer and things run better without restriction. 
 
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03 Sep 2023 17:44 #279743 by Kosmas
Hi again.
While i was reading the "Hardware latency tests, used PC's" posts in forum, in page 10, there is a post (at 19 May 2021 17:32) by "TheFarfar" about an Asus P5B-MX, Intel Core2 Quad Q6600, 4 GB RAM.
Your comment was "That looks very good even for software stepping."

There is a PC exactly like this in Athens Greece (i am in Crete) at 50euros + 12Euros shipping cost.

I thing i have to bye it asap. It is ok for what i am going to do (XP-Mach3-USB card) and looks perfect for what i am "dreaming" to do (Linux-Mesa 7i96S)

What do you thing?

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03 Sep 2023 17:53 #279745 by tommylight
Seems OK, but it is old and might have issues, caps can cause havoc as they dry out with time.
I still have an Asus P5B Deluxe with Intel Q9400, it still works but already shows issues, like not rebooting whet you tell it to and requiring a hard reset, or fails to boot and needs again a hard reset.
Try to find a Dell 980 or HP 8300 USDT, Dell tower also has parallel port so you can throw the "mach3 usb" :)

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03 Sep 2023 18:08 #279752 by Kosmas
Thanks, thanks, thanks ......

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03 Sep 2023 18:44 #279755 by Kosmas
Sorry when you say 980?

Dell Optiplex 980 MT i5-750/4GB/250GB/Quadro FX580
Dell Optiplex 980 SFF i5-650/4GB/250GB/DVD
Dell OptiPlex 980 DT Core i7-860 2,8 - SSD 128 Gb - 4GB

Dell Optiplex 980 MT i5 €55
CPU: Intel® Core™ i5-750 2.66GHz(8M)
Socket: LGA1156
Chipset: Intel Q57 Express chipset
Memory: 4GB DDR3
# of DIMMS: Two (2)
HDD: 250GB
ODD interface: DVD-RW SATA
Bays: (2) 5,25 External, 3.5 External, (2) 3.5 Internal
VGA: Nvidia Quadro FX580 512MB
RAID Controller: No
Front I/O: (4) USB 2.0, Audio I/O
Rear I/O: (6) USB 2.0, Audio I/O, RJ45, VGA, (2) PS2, DP, Serial
Slots: PCIe 2.0 x16, PCIe 2.0 x4
LAN: Gigabit 100/1000
Integrated Audio: HD audio (PC speaker)
Dell Optiplex 980 SFF i5 Intel® Core™ i5-650 3.20GHz (4M) €55
CPU: Intel® Core™ i5-650 3.20GHz (4M)
Socket: LGA1156
Chipset: Intel Q57 Express
Memory: 4GB DDR3
# of DIMMS: Four (4)
HDD: 250GB
ODD interface: DVD SATA
Bays: (1) 5.25″ external, (1) 3.5″ external, (1) 3.5″ internal
RAID Controller: Yes
Front I/O: (2) USB 2.0, Audio I/O
Rear I/O: (6)USB 2.0, VGA, DP, RJ-45, Audio I/O
Slots: PCIe 2.0 x16, PCIe 2.0 x4
LAN: Gigabit 100/1000
Integrated Audio: HD audio (PC speaker)
Dell Optiplex 980 DT i7 €250
Memory: 4 Gb DDR3
Intel Core i7-860 2,8 GHz
Intel HD Graphics 2000

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04 Sep 2023 00:08 #279770 by tommylight
I will check tomorrow, i still have 2 of those.
Have good latency even with the RT kernel, never needed RTAI for these.

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04 Sep 2023 02:19 #279776 by Marcodi
Hi, the MSI - P45 will definitely run this' I ran on similar gigabyte P45 for more than 10 years my linuxcnc in combination with Mesa cards. The other 4 I would personally not use , its older and you do want some reaction from the computer.
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04 Sep 2023 02:26 #279777 by Marcodi
The Q6600 will absolutely be able to run your linixcnc with mesaboards, all my Linux is running on these kind of obsolete computers that work perfectly fine for linuxCNC, so don't spend money on computer hardware. Save it for the real magic.pieces, the Mesa Cards.

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