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date: 3:21:14, June 20, 2021
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Welcome, my name is Emmanuel Roberto Richiardone, this is my place on the web.

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Save old plastics from ugly yellowSun, 26 Jul 09
A common problem of old plastics is their changing of colour, especially the original white-beige becoming clearly an ugly yellow. This phenomena, accelerated by the sun exposure, is really noticeable on old computers case.
A chemist analyzed the problem and started the the Retrobright Project in the effort of saving old plastic from decadence.
In facts the guilt is a chemical element, the bromine, that is added as a flame retardant: this component with UV light start a reaction and the plastic became more and more yellowish.
For the safe of us all the guy found a cure, a solution of water and hydrogen peroxide, that you can make at home with some commercial available product: simply submerge the plastic in it and you give a chance to yous plastics to born again!
++freebsdMon, 8 Jun 09
A nice trick, from Colin Percival, enable you to remotely replace a GNU/Linux system with FreeBSD. This script use the swap space of a running linux to write a FreeBSD ISO image and some executable stuff; after running the script, you reboot the linux machine and it starts as a FreeBSD one loaded into memory. You can then access the system via SSH and proceed with a classic installation.
The script is called depenguinator 2.0 and the reference page is here.
30 anni di spamSun, 7 Jun 09
Brad Templeton raccoglie una serie di interessanti documenti su quelle fastidiose email non richieste chiamate spam.
Il primo "spammer" era probabilmente un impiegato della DEC, che decise di inviare un invito ad una presentazione a tutti gli indirizzi del mid-west su ARPANET. La storia completa e` qui.
E` interessante leggere alcune osservazioni, per esempio quella di Stallman, che prima si lamenta di non averla ricevuta e poi cambia idea :P
AdSense with picturesMon, 1 Jun 09
Google have accustomed us showing ads without colored banners of 90's era, but now it's over. Like many cyclic things, beginning with adsense link pages we have to tolerate image banners.
Oracle eat SunMon, 1 Jun 09
A month ago I've heard about Oracle to buy Sun.
At first I was surprised, I know about dramatically loss of sales in hardware section of Sun, but Sun led a lot of big software project. Clearly Oracle is interested in selling a complete database system, from hardware to database applications.

The deal is not yet closed, but the future of a company that engineers good hardware (as it happened years ago with DEC) and a promoter of open-source software is unclear; and hearing not much details around let me pessimistic about the open-source projects...
Google Maps shotsSun, 25 Jan 09
Sometimes peoples worries, rightfully, about Google Maps in-life intrusion; recently in particular about Google Streetview; someone already invented the robots.txt 2.0 protocol.
But what about the buyers and sellers at this open market in Africa, or those deers, and these sheeps!
Hey, what's that?Fri, 23 Jan 09
I propose this really interesting website: www.heywhatsthat.com.
Despite his bizzare name, it's what I can define a panorama profile simulator. Making extensive use of Google Maps, it represent you the profile of earth-sky division for any place, and let you know if another place is visible or not. And you can also make the viceversa, from the profile know where the place is.
100BaseTTue, 20 Jan 09
Siccome mi sono stufato di sentire e di leggere un po` ovunque diverse teorie sulla lunghezza massima di un cavo Ethernet 100BaseT, faccio un po` di chiarezza.
Il 100Base-T (o meglio 100Base-TX Full-Duplex, questo si utilizza oggi) e` uno standard di interfaccia fisica (livello 1) per il collegamento di una rete Ethernet; esso e` definito sia a livello elettrico, sia fisico che protocollare nella seconda sezione dello standard IEEE 802.3-2005.
Riporto da pagina 280: "Unlike half duplex CSMA/CD networks, the physical size of full duplex 100 Mb/s CSMA/CD networks is not limited by the round-trip collision propagation delay. Instead, the maximum link length between DTEs is limited only by the signal transmission characteristics of the specific cable, as specified in Table 295.", poiche' infatti essendo una coppia di fili per TX, ed una di RX, il mezzo non e` condiviso come sul Thick/Thin Ethernet oppure l'Half-Duplex.
Si parla quindi di un massimo di 100 metri con cavo bilanciato ISO/IEC 11801 Classe D; questo standard ISO presuppone indifferentemente un UTP (Unshielded Twisted Pair) o STP (Shield Twisted Pair) Categoria 5, con un'attenuazione massima del 20%, per cui tipicamente, con poca interferenza, si richiede un 24AWG oppure 26AWG di diametro.

Conclusione:
non essendoci restrizioni protocollari, utilizzando un cavo bilanciato con attenuazioni piu` basse da quelle mimime richieste in verita` con il 100Base-TX FD si puo` fare piu` di 100 metri. Con le cautele:
  • lo standard riporta anche specifiche massime per quanto riguarda i ritardi, che dipendono da un sacco di fattori (potrei stare ore qui)
  • gli apparati devono comunicare subito con questo protocollo, senza negoziare altri protocolli Half-Duplex
  • bisogna fidarsi da chi costruisce il cavo, poiche` Categoria 5e o 6 e` un po` generico...
  • nel conteggio dei 100 metri non sono inclusi eventuali cavi patch o giunti, che sicuramente attenuano il segnale
Per cui come nota personale essere conservativi non guasta mai, ma se bisogna fare piu` di 100 metri un buon cavo e un po` di prove prima non guastano.

PS: Anni fa` si parlava di massimo 90 metri. Questo dipende da un'approssimazione dovuta alla diatriba tra ISO/IEC e TIA/EIA: 300 piedi che sono 90 metri. C'e` chi parla anche di 100 metri srotolati, etc etc chi piu` ne ha piu` ne metta.
Shoes...Sat, 17 Jan 09
What a strange browsing path I followed, I've found this strange Ian's shoelace site.
Here you will find every sort of lacing and knot techniques, but really *every* sort, with pictures, detailed howtos and comments. Very interesting the really fast "Ian Knot", but it's not very simple as it seems.
Sci-fi papercraft!Fri, 2 Jan 09
Last night I've found this astonishing papercraft website http://aliens.humlak.cz/
Maintained by a prolific Czech guy, the collection of science-fiction items that you can made yourself is really impressive, starting from every Aliens objects to Tron Light-Cicles, passing through Metroid, Robocop, Terminator and so on!
I'm preparing a lot of paper and glue, but... uhmmm where I've put my old inkjet color printer??

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