Is LinuxCNC just for networked PC's ? Gurus ?

Sorry for any confusion. I was trying to be complete and accurate.

2.7.4 would not install.

The Linuxcnc.org site suggested "users are encouraged to upgrade" (to 2.7.4).
The change list seemed like a lot of bugs were fixed and that seemed like a good thing.
So that's why I tried that. It would not load. It was never clear to me why it failed.
Is there any issue getting it to load/run on an AMD Athlon 64bit CPU on an ASUS motherboard?

I did get 2.6.4 to install (from a USB stick). That where I'm at now.
But then, again on the Linuxcnc.org site it says 2.4.16 is released.
Again, the change list makes it seem like a lot of bugs were fixed and that seems like something I should install.
Is it?

If I got that done then what would I be missing if I did not get 2.7.x running?

I see that the 2.5.x is no longer supported. If I stayed with 2.6.x I'm sure it will eventually be unsupported. That's progress, right? I don't especially care/need more features, but I don't like bugs. To me 'bugs' means that there is a potential some day for my machine to hiccup and be damaged or scrap a part; that's bad. It seems like chasing version numbers is one way to reduce bugs; is it not? Wouldn't I want a version with a large third digit (a.b.99) ?

If I have 2.6.4 running would it not be prudent to either get 2.4.16? (maybe, maybe not, I'm not being rhetorical, I'd like your opinion).

The Linuxcnc.org site suggested "users are encouraged to upgrade" (to 2.7.4).
The change list seemed like a lot of bugs were fixed and that seemed like a good thing.
So that's why I tried that. It would not load.

Fine, but what I am trying to point out is that you did NOT try to upgrade 2.6.4 to 2.7.4.

What you tried to do is overwrite your partion with a debian based distro which had 2.7.4 bundled with it.

Read the upgrading document I linked to and try to upgrade linuxcnc, whilst keeping the OS and kernel you already have.

It should be no more involved than changing the apt repo info.

Update:

I read something on this forum about SanDisk USB sticks having some issues like maybe hidden junk that could cause issues. I've NOT been using SanDisk. I have 2 Samsung 16GB SDHC/Class-10 cards in USB adapters that I have been using without problems for a year. I also have a Lexar 1GB and a Kingston 8GB. I never had problems with any of them. I used them in 3 cars, a NAS drive, a Mac and 5 different PC's.

First some history:

I loaded the old LinuxCNC 2.5.0 iso on the Lexar 1GB because it would fit. When I tried (the first several times) to load LinuxCNC 2.7.4 iso I went to the Samsung 16GB because the iso was 1.1GB. That failed to load. I later used that same stick with an actual Debian 7.9.0 and that loaded without any problems. I tried 2.7.4 again (graphical install) and it failed. So I decided to try a 2.6 iso and found the 2.6.4 iso; downloaded that, put it on the Sansung 16GB stick (always using Linux Live software, LiLi). And it loaded. Wow. That would indicate no problem with the stick since both Debian 7.9.0 and the LinuxCNC2.6.4 iso both loaded okay.

Meanwhile ArcEye has been trying to help me. (THANKS for that!), Never the less, something was still not perfectly square with me. I.e. why was there ANY problem loading a bone stock LinuxCNC iso onto a very typical PC (<=3yrs old). I was thrown off track for a while by seeing posts where there seemed to be some issues with later (2.7.x) versions running on 64 bit CPU's (like my AMD Athlon 64). Maybe that was a wild goose chase, I still don't know.

Now:
This morning I remembered that piece about SanDisk and USB's. So I used LiLi and loaded LinuxCNC 2.7.4 onto my Kingston 8GB USB stick. (I never had any luck with infrarecorder) I walked out to my garage and started that PC with the Kingston 8GB USB in a back-panel USB slot and held F8 until the boot menu came up. I selected the Kingston (I always select it as a "classic" USB, never as a UEFI USB) and ran the graphical install. I just clicked off all the defaults until it came to the progress bar where it was installing the main system (where it previously bombed out) and my eyes got bigger as it passed the 1/4 to 1/3 point where it bombed before. It went to 100% finished and then completed the remainder of the install. Eureka!!! Now I have 2.7.4 up and running.

I started the Latency Test, I started 5 copies of glxgears, I opened LibreDraw and scribbled, I opened a terminal window, I opened some other app. I spread them in the 4 different windows. Then I watched the latency numbers. After 20 minutes they never climbed above 18,998 ns. With 2.6.4 they went to about 25,500ns.

Hopefully it's okay now. Hopefully there may have been some issue with the Samsung SDHC card that allowed it to work sometime but not always. Perhaps it was 'marginal'.

You are correct. i did not try to upgrade 2.6.4 to 2.7.4. I had 2.5.0 and the directions said NOT to go from 2.5.x to 2.7.x without loading 2.6.x first. Instead (also according to the web site) I tried to do a full iso install of 2.7.4 and with repartitioning/formatting the entire drive in the process. I assumed that would wipe out the old 2.5.0 stuff and do the 2.7.4 install as if it were a virgin PC.

I always did a full iso install. I never tried an 'upgrade'.

Even after I had 2.6.4 successfully installed - see my last post - I again tried a full iso install of 2.7.4. I was afraid NOT to do the full install because I don't know enough Linux and if something didn't work and I had to go back to 2.6.x then would something have been left over from an attempted upgrade to 2.7.4 to mess up the 2.6.x. Doing full installs of version X seemed like the only way for me to be reasonably assured of having a full sets of appropriately matched softwares.

Nevertheless, thanks for your help.

Doing full installs of version X seemed like the only way for me to be reasonably assured of having a full sets of appropriately matched softwares.

That is not correct and I have linked the document that someone (probably JT) spent time and effort producing, which shows exactly how to upgrade 2.6 to 2.7

Or you can ignore the advice you asked for and go round and around in loquacious circles.

The choice is yours.

Here the terse version:

It is difficult for me to do some of the things which JT or anybody posted because I don't have a network connection and obvioulsy I am stupid about Linux.

I said "seemed like the only way for me to be reasonably assured" not anyone else.

I asked for advice about non-networked solutions but got none. My choice would be to follow advice about what I asked for.

I will not post any more about not having a network on my cnc machine's PC.

Thanks anyway.