Say what? [LWN.net]

Say what?

Posted Jun 12, 2009 12:39 UTC (Fri) by robert_s (subscriber, #42402)
In reply to: Say what? by sbergman27
Parent article: Linux first to offer USB 3.0 driver (Linux Devices)

"And why are we still quoting speeds in terms of bits per second in the year 2009? I thought we agreed upon a standard size for a byte a while back, and the proponents of '7' lost?"

Nope. That's not how it works. Take 8b10b coding for example. It takes 10 bits to transmit a(n 8 bit) byte, so the raw bitrate is indeed ten times that of the datarate.

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Say what?

Posted Jun 12, 2009 15:10 UTC (Fri) by k8to (guest, #15413) [Link] (1 responses)

That wouldn't stop us from quoting in bytes. It complicates the picture a bit, but there are plenty of complications.

Say what?

Posted Jun 20, 2009 20:33 UTC (Sat) by giraffedata (guest, #1954) [Link]

That wouldn't stop us from quoting in bytes.

But bytes aren't a unit of measure to be quoted. They're units of data.

8 bits don't make a byte like 12 inches make a foot. It's more like 24 beers make a case. You could point to a keg of beer and say it contains 6.9 cases of beer, but in fact there are no cases of beer in it.

Computer memory and disk sectors, on the other hand actually have bytes in them.

It complicates the picture a bit, but there are plenty of complications.

Co-opting the word "byte" as a unit of measure does complicate the picture, and it doesn't make anything less confusing, because there are so many levels on which to count the bits. Most people would say it's fraudulent to say 5E9/8 bytes travel down this line every second, since less than 80% of that number end up as actual bytes in computer memory.

The only unambiguous measure you can give is the raw bit signalling rate. Try to get more real-world than that, and you have to get specific about which real world you mean.