Megabytes per second was (as you will remember) on parallel comms interfaces where there would be one (8 bit) byte of data sent across 8,9 or 10 parallel data lines with two providing some form of parity capability or with 16bit byte systems across 18 or more data lines. Plenty of ambiguity there.


And definitely "bits" is the only non-ambiguous way. Even kb & Mb are ambiguous!

In reply to a post by mrpaperclip:

Why do speeds still get quoted in bits per second? Its like saying my car does 193,121,280 mm per hour..... or 193 Mmmph

No, Mm - Mega-milli is not an acceptable prefix. 10⁶ x 10^-3 = 10³ or k - kilo. So your car does 193 kmph or kmh^-1

Shouldn't it be K|M baud anyway? Or was that only used for analogue systems?

Edited by deleted (Sat 04-Aug-12 16:13:36)

No that's the symbol rate and a symbol can represent several bits.

A nice long discussion here.

Baud is symbol rate. For most UK broadband, it would be a fixed 4 kBaud service - all ADSL standards deployed in the UK, plus the VDSL2 used by BT FTTC is 4kBaud, but with many bits per symbol to get the data rate up - 80M service is over 20 kilobits per symbol.

Cable is a slightly different beast - because it's not an OFDM (aka DMT) system, it uses many more symbols, but typically only 8 bits per symbol. At the data rates used here (around 56MBit/s/channel), you'd get 7 MBaud.