At 05:17 PM 1/20/2004, James Newton, Host wrote: >Why is each higher baud rate twice as fast until 14.4K which is only 1.5 >times faster than 9600? > >115,200 > 57,600 > 28,800 > 14,400 > ? > 9,600 > 4,800 > 2,400 > 1,200 > 600 > 300 You forgot 75 & 150 . Also 19200 & 38400. You sparked an interesting discussion but I *think* that you are actually talking about 2 different issues: standard baud rates that a UART can use, and connect speeds that a modem might use. The UART issue is simple - standard baud rate generators as used in most PCs only have a certain number of divisors that can be used when dividing the crystal rate down to the clock input of the UART. I could be wrong on the following (probably am - but hopefully someone else can correct my mistakes) - I *think* that the 2 'odd-ball' baud rates of 57600 & 115200 come from using a divide by 3 tap in the baud rate generator instead of only using powers of 2. Others have covered the reasons for the different modem connect speeds over TELCO lines. One thing to remember: the modem communicates to the PC using one of the standard baud rates only: 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu