Tuesday, October 10, 2006

Computer's archeology

Last week I reformed 2 old COMPAQ computers from an old client of mine.
They were messing up the machine room and I decided to get rid of them once for all. Nevertheless I accorded them some attention, like I should have done with old working horses before sending them to the butchery.
These machines has been used for years with NetWare 3.11 SFT III then NetWare 4.10 SFT III. For the youngers, SFT III stands for System Fault Tolerant, III being the upper level.
The principle was to create a virtual server upon two physical ones. The 2 computers were doing exactly the same thing and one of them was responding the client request after ensuring they were coherent. A pretty smart system. The 2 computers were linked with a dedicated high speed LAN connection, and that's the point I stumbled upon more particulary.

They were 2 LAN adpaters in each computer : a 10 Mb Ethernet link for the standard LAN attachement and a Thomas Conrad 100 Mb ARCNET adapter for the dedicated link. And guess what : first of I kept the TC cards for me as souvenir and second I would like to emphasize on the following :
  • both cards were manufacturated in 1994, EISA bus.
  • the Ethernet one was a full lenght card - remember the one that occupied all the place from front to back of a standard PC case - and it was full of chips, no room left at all on it !
  • the ARCNET one was a short one with one main chip and a plenty of room on it.
So what ?

Well, ARCNET technology is able to make circles around Ethernet.
It has been and it is a much more efficient technology, you can integrate it on some 25000 transistors or so far, against perhaps 250000 for Ethernet, beside ARCNET protocol (layer 2) is much more efficient and one which is precisely able to met isochronous requirements some traffic like voice are begging for.
In fact what is happening with Ethernet ?
The original layer 2 protocol CSMA CD is no more used, it is been killed by use of switchs in which we are desperately trying to incorporating - by sofware - the intelligence which is lacking to layer 2 protocol. What is left to Ethernet is a frame format, and layer I encoding and transmission.

What happened to ARCNET ? Why the technology almost disappeared if it were so good ?
But I don't want to mess up everythings, I will explain what marketing is really in another post.

Stay tuned !

Notice the gentleman on the upper right ?
It's John Murphy ARCNET Chief Architect, let pay him and his colleagues a little visit :
The photo Copyright © 2002 ARCNET Trade Association

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