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*To*: jenkins@xxxxxxxx, stds-802-3-hssg@xxxxxxxx*Subject*: RE: Maximum run length of 64/66b*From*: pat_thaler@xxxxxxxxxxx*Date*: Mon, 4 Dec 2000 16:14:14 -0700*Sender*: owner-stds-802-3-hssg@xxxxxxxx

Mike and Shen, Sorry I didn't get to answering sooner. I was busy getting clause 49 ready for D2.0 and other tasks. The maximum run length is 66 which can occur when a data frame is followed by a control frame or vice versa. There is always a transition between the two bits of the sync header. The probability of a run of 65 or 66 bits is 2^64 ~ 16 * 10^18. One can AC couple just as one can with any scrambled code. On the average about half the bits will be zero and half will be one. The cut-off frequency will be much lower than for something like an 8B/10B code, but it does not have to go down to zero. Regards, Pat -----Original Message----- From: Mike Jenkins [mailto:jenkins@xxxxxxxx] Sent: Tuesday, November 14, 2000 2:45 PM To: stds-802-3-hssg@xxxxxxxx Subject: Re: Maximum run length of 64/66b Hello, Perhaps I missed it, but I haven't seen any responses to the question below, so let me hazard a guess and hope that someone corrects me if I'm wrong: 1) The max run length is 66, since the sync bits are not scrambled. 2) I suspect the frequency content is sufficiently low that any AC coupling would be impossible. Improved theoretical or empirical results might help 64b/66b serve other applications as well as this one, I would think. Opinions anyone? Regards, Mike ss_shen@xxxxxxxxxxxxxxxxx wrote: > > Hi : > > This maybe a silly question, but if someone can > tell me, would be much appreciated. > > (1) the Maximum run length of 64/66b: > Before scramble, the worse run length is > 65 when it has 01111...... (one "0", 65 "1"). > What would be the maximum run length after > scramble? > > (2) DC balancing aspect of 64b/66b + scramble > > thanks in advance. > Best Regards > steven Shen > Silicon Bridge -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Mike Jenkins Phone: 408.433.7901 _____ LSI Logic Corp, ms/G715 Fax: 408.433.7461 LSI|LOGIC| (R) 1525 McCarthy Blvd. mailto:Jenkins@xxxxxxxx | | Milpitas, CA 95035 http://www.lsilogic.com |_____| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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