On Wednesday 04 February 2009, Jim Fleig - CNC Services wrote: One subject clarified at the bottom. >Hi Steve, > >Thank you for the reply and answers. > >Questions inserted into your reply below. > >Jim > > >----- Original Message ----- >From: "Stephen Wille Padnos" <[email protected]> >To: "Enhanced Machine Controller (EMC)" <[email protected]> >Sent: Tuesday, February 03, 2009 9:34 PM >Subject: Re: [Emc-users] I was able to boot from the CD, thanks for all the >information. > >> Jim Fleig - CNC Services wrote: >>>Many thanks for all the information. >>> >>>Is it possible to create a configuration and make a CD to demonstrate how >>>a >>>machine would function if retrofit with EMC? >> >> You can't save a configuration to the CD, > >I'm not arguing. This is a sincere question. If a CD is a R/W CD, would it >be possible to erase some of the applications that are not needed for EMC >like Games? Would it be possible to erase configuration files that are not >needed and write a configuration to a R/W CD? > >> but if you have a USB memory > >I do. > >> stick, you can make a copy of a config > >Does EMC have to be installed to create a config or can this be done while >using the CD? > >> (in your home directory, which will be in ramdisk), > >I don't understand the statement about home directory and ramdisk. This is >what I think I know: computer turns on, bios in a prom on the motherboard >has a limited set of instructions that the computer follows to locate the OS >that will run the computer, OS is found and takes over computer operation >(example: XP). When the OS is up and running, then other programs can be >selected which have commands of their own to use computer resources while >the OS oversees all of the currently running programs. When a computer >boots and the bios sees that there is a source of OS in the CD drive or on a >USB channel, it allows that OS to run. Here is where it gets fuzzy for me. >While running the Ubuntu CD it was possible to open the Word Processor >application. If a document was created while that application was open >would it be possible to save the document? If yes, where? If the CD being >used were a R/W CD then it would make sense to me (although it might not >actually work) that the created document could be saved on the CD. It >doesn't make sense to me (keep in mind that I don't know what I'm talking >about, I'm just sharing my impression) that created data could be saved >using the hard drive, a USB memory stick, a floppy drive (yes, I have one >plugged into a USB port for old stuff I have to reference occassionally) or >a second R/W CD drive. This doesn't make sense to me because I don't >understand how the OS running on the CD would have the drivers to manage the >USB ports, other CD drives, etc. > >> then copy that to the USB stick. Later, when you >> go to do the demo, you can boot from liveCD, and copy the config back to >> your ramdisk home directory and select it from the config picker. > >Once I understand the directions above this will probably be as simple for >me as the file copy and paste that I do so often now. At the moment, I >don't understand the statement above. What is the ramdisk home directory? > >> There are other ways to do this which are more transparent (things >> written to the file system automatically end up on the USB stick), but >> that's a bit harder to set up and is probably not needed for this purpose. >> >> - Steve > >Thank you for all of the explanation above. Ideally (I don't know if this >is possible) it would be possible to send someone a CD, they would boot from >the CD, EMC would auto load, they would be able to follow hardcopy >instructions that came with the CD and perform manual and MDI functions and >load a program and run it with EMC. Am I dreaming? If no, what is needed >to make this happen? > >Thanks again for all of the answers. This is an area where I obviously am >uneducated but willing to learn. :-)
Jim; It appears you see the RW marker on the CD as indicating it is capable of a random access rewrite. They are not. Yes, the whole cd can be re-written, but not a single file in some random location. This is why you will need to mount the usb stick and save the generated data there, then take both the cd and the usb stick to the next machine, or to reboot and restore on that one from the stick. One of the speed problems is the difference in the physical track format. Where a hard or floppy disk has discrete tracks (and knows where they are) that the head can position itself over and read the complete track, there is no arbitrary track number on a cd or dvd, they are one long, continuous spiral track, from the inside out. So when a cd/dvd drive needs to find something, it knows the logical sector number of where the data is at, but generally will calculate how far in or out it has to move, stop, let the servo find the track center, read the data to see if that block is near, and if not, move some more, read, rinse, lather and repeat till it has been found. Once found, modern drives can approach a slow hard disk in data speeds, but the looking for it is what takes the majority of the time. They also try to maintain a steady linear speed of the track, and if the move in or out is a long one, it will speed the disk up or slow it down to fit the data recovery circuitry before handing the computer the requested data. When you hear the disk whirring at a good clip, say 10k+ rpms, it is near the start at the inside of the disk. I read someplace that scratched cd's have been known to explode at those so-called 52x rpms. -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) You prefer the company of the opposite sex, but are well liked by your own. ------------------------------------------------------------------------------ Create and Deploy Rich Internet Apps outside the browser with Adobe(R)AIR(TM) software. With Adobe AIR, Ajax developers can use existing skills and code to build responsive, highly engaging applications that combine the power of local resources and data with the reach of the web. Download the Adobe AIR SDK and Ajax docs to start building applications today-http://p.sf.net/sfu/adobe-com _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
