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March 26, 2012
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I can think of at least a dozen applications for this little Linux-based computer, and I just can’t believe the price! There is a Raspberry Pi Fedora Remix available as well.
Raspbian, Debian Linux for Raspberry
August 13, 2011
Once upon a time, I had the need to make ethernet cables as a part of my job, crimping the little plastic connectors on the ends of bulk Cat 5 cable. I no longer work in this area of information technology, but I’ve recently found it necessary to renew and extend my knowledge if network cabling for other reasons. Here are some handy resources and notes.
RJ stands for “Registered Jack” and the succeeding number designates the standard wiring pattern used (a.k.a. pinout). Despite popular demand, this designation does not refer to the physical jack or connector. The connectors are actually named for the number of positions and conductors. For example, RJ-45 cables used for data networking use an 8P8C connector, whereas RJ-45 cables once used for telephony used an 8P2C connector. Similarly, wall-to-phone cables are either RJ-11 or RJ-14, which use 6P2C and 6P4C connectors respectively; the former has only one pair of wires to support one phone line and the other has two pair to support two lines.
Unshielded, twisted-pair (UTP) cable is categorized based on its physical properties. The main practical difference is speed. Cat 3 is used for telephony and 10BASE-T networking, Cat 5 can support 100BASE-T, 5e can support 1000BASE-T (Gigabit), and Cat 6 supports 10GBASE-T.
Cat 6 may include a better grade of wire than Cat 5, but the performance increase results primarily from improved insulation; thus, the connectors must accomodate the larger jackets or performance may be degraded due to poor assembly.
I’m not going to memorize these, so a good reference is always welcome.
Telephony. The colors of the wires for positions 1-6 are W/G,W/O,Bl,W/Bl,O,G. RJ-11 uses only conductors on positions 3 & 4, RJ-14 add positions 2 & 5, and RJ-25 use all six. The old colors are W,Bk,R,G,Y,Bl. Wikipedia has a very good table detailing these pinouts.
Ethernet. Ethernet follows the TIA/EIA-568 standards, either “A” or “B”. The order of the colors is different, but the order of the pairs is identical. [I've always seen T568A, but then, it's not like I look at the pinouts on network cables every day.] For T568A, the colors for positions 1-8 are W/G,G,W/O,Bl,W/Bl,O,W/Br,Br; for T568B, swap all of the greens for oranges in the list above. Again, Wikipedia has a very good table for detailing these pinouts.
The Best Wiring Diagrams
Good pictures are always better – or at least quicker – to use than to have to decipher the orders of wires above. The best wiring diagrams I’ve found for wiring the more popular male connectors are published by Huffman Reference Materials. They even offer free PDF downloads showing the pinouts for several RJs on 6PXC and 8P8C connectors.
The diagrams on Project Resource Solution’s website are also very clear.
April 17, 2011
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I recently, at the time of this writing, have obtained a Neoware CA19 thin client from a friend in whose garage it had been collecting dust. I’ve always been interested in the thin client architecture, but have never seen an implementation outside of one local library. Here, I collect links and notes to information about Neoware thin clinets in general.
The naming conventions for CA19 specifically and some good modding advice.
Much more to come…
June 28, 2010
When I finally committed to using Linux exclusively for my personal computing, I had just bought a new laptop and installed Ubuntu over the existing Windows partition. I removed the Windows badge from its place near the keyboard, but felt like something was missing. I looked online for Linux badges and found several listings on eBay. The best were from a shop called Funkyputers. I bought a lot of ten, including some bearing the logos of other distributions, just in case I decided not to stick with Ubuntu. The quality wasn’t quite as good as the labels stamped for manufacturers, but they’ve lasted surprising long without much fading. After running across a half-page ad that was shipped with my order, I thought I might order some new badges for the family’s new netbooks, only to find that Funkyputers is no more.
Contact info for Funkyputers included:
- 9 Cranbrook Street, Cardiff CF244AL, UK
I believe this was a sole proprietorship owned by one Tausif “Puck” Rahman. He’s the fellow that handled my order, and after looking up the company’s mailing address on Google Maps, it looks like it was probably run out of someone’s flat in Cardiff, in southern Wales. Puck seemed like a very nice fellow and I hope all is well with him.
August 30, 2010. I was recently contacted by one of Puck’s business associates as a result of this post. It seems that his decision to close shop was sudden and may have been motivated, at least in part, by personal circumstances. Whereas my correspondance with Puck was very brief, this particular customer had an ongoing business relationship with Puck and was able to determine that Puck was ok. He also recommended ScotGold Products in Aberdeenshire, Scotland for similar products. I’ve not had a need to shop there myself yet, but I’ll certainly give them a try when such a need arises.
July 20, 2009
The Zen media player by Creative Labs seems to be a bit picky about the video formats it plays. After a lot of experimentation and little success, I eventually found the ZEN / ZEN Vision Series Video Encoding Guidelines. When I have time to play with it again, I plan to add to this post the methods that work best for me.
June 29, 2008
Here’s my thoughts on a Linux-based headless web client:
- MiniKnoppix would be a good platform, but the following packages would have to be readded: anacron, expect, html2text, m4, ndiswrapper.
- Knoppix has a “persistent home” option.
- The JFFS filesystem will distribute wear on a Compact Flash drive.
- Fetchmail & procmail could be used to retreive simple text info by cell phone or IM.
- “Web Client Programming with Perl” & “Spidering Hacks” by O’Reilly publishing would provide much help in scripting scrapes and other tools/toys.
February 18, 2008
At the time of this writing, many laptops, including Dell and HP/Compaq, contain Wifi cards made by Broadcom. In the past, there has been no ‘official’ driver written by Broadcom for these devices for Linux. A tried and true way of using these cards with Linux is through the use of the NDISwrapper utility.
- Install NDISwrapper package if not already installed.
- Download the Wifi drivers from Dell, Compaq, etc.
- Extract the necessary files (e.g. bcmwl5.inf & bcmwl.sys). This may require running a “self-extracting” file under Wine.
- Install the driver: sudo ndiswrapper -i /dir_path/bcmwl5.inf
- Verify the hardware is present: sudo ndiswrapper -l
- Load the driver: sudo modprobe ndiswrapper
- Update the configuration: sudo ndiswrapper -m
- NDISwrapper homepage: http://ndiswrapper.sourceforge.net/
- NDISwrapper manpage: http://linux.die.net/man/8/ndiswrapper
- Another copy of these instructions: https://www.scientificlinux.org/documentation/howto/ndiswrapper.broadcom