Date: Fri, 2 May 1997 10:32:06 +0200 From: Stefan Esser <se@FreeBSD.ORG> To: Ben Black <black@zen.cypher.net> Cc: hackers@FreeBSD.ORG Subject: Re: USB support? Message-ID: <19970502103206.40003@x14.mi.uni-koeln.de> In-Reply-To: <Pine.LNX.3.91.970501203010.1806A-100000@zen.cypher.net>; from Ben Black on Thu, May 01, 1997 at 08:31:15PM -0400 References: <19970501222111.34624@hw.nl> <Pine.LNX.3.91.970501203010.1806A-100000@zen.cypher.net>
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On May 1, Ben Black <black@zen.cypher.net> wrote: > not sure why they'd be rare in europe, but i got my first USB board last Ahemm ??? Thought these Taiwanese PC motherboards were sold to the US and Europe around the same time ? > year (in about august) and i have 2 more now. also, if you are using it Sure, non-functional USB had been put into motherboards for quite some time, already :) As of December 96, most motherboards still came without actual USB support (the chips contained USB logic, but it was disabled for technical reasons). In March 97, some 50% of the Pentium boards came with functional USB, but most required you to buy an optional USB connector (even some USB boards, which should have offered that connector on the board's I/O panel). As of now, just about every motherboard comes with USB logic, but the majority reqires you to buy additional connectors, still ... > to network home PCs then who cares if there are any devices? USB for networking ? Well, USB is designed for quite a different purpose, I'm afraid ... Did you have a look at the (freely available) documents that currently define USB and the protocols and device classes supported ? It offers about the same aggregate throughput as 10MHz Ethernet, but it is designed more like a serial I/O bus, where specific devices are addressed from the USB controller in the chip set, instead of over the PCI bus. USB works more like HP-IB (or SCSI) than Ethernet, and while it is in fact possible to construct an network on that base, it is hardly ever done. Hmmm, you could probably use USB for PPP, I guess ... Anyway: I did look at USB some time ago, and I think that is should be supported to connect devices like scanners, printers, sound, frame grabbers, mice, ISDN and modems, most of which currently are connected over some kind of parallel or serial port. USB requires kernel support for its (quite complex) queue management and real-time features, and all actual device drivers most be layered on top of this. Since you need USB hubs to connect more than two USB devices to a motherboard, you'll possibly end up with a more expensive networking solution than with plain old Ethernet, and at reduced functionality (its hard to beat the cost of 10base2 in a home environment: $25 for a PCI Ethernet card and less than $10 for some 20m (60ft) of cable and the two 50Ohm terminators). I want to implement trivial USB functionality as soon as I finish building up my new Triton II based system (with USB). Still waiting for an AMD K6 ... Regards, STefan
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