Re: 64B/66B Control Codes Mapping & Bit Order
Gee Howard,
You make me feel like a kid again!
Thanks old man ;^)
Ben
Howard Frazier wrote:
>
> Ben and Pat,
>
> Your exchange makes me feel old and crusty. 22.2.3.2.1 was written a mere
> 7 years ago! But that is an eon in internet years, so now it is part of the
> "long history" of ethernet standards, having earned its way into the
> hallowed scripture.
>
> It's like having one of your kindergarten finger paintings hung in the
> Sistine Chapel.
>
> The message to all of you whippersnappers out there is that you should
> be very careful about what you write. Someday, it might be treated as
> gospel, even if you didn't have a clew when you wrote it. The other
> message is that precedent is a wonderful guide, but you don't have
> to be a slave to it. Better ideas come along every day, and those who
> went before you may have made their decisions on the basis of less
> information than you possess today.
>
> Please pass the tapioca and warm milk.
>
> Howard Frazier
> DomiNet Systems, Inc.
>
> Ben Brown wrote:
> >
> > Pat,
> >
> > Given the long history that you reminded me of, I'll drop my
> > request. This bit ordering has always confused me but I agree
> > that we probably shouldn't change it.
> >
> > Ben
> >
> > pat_thaler@xxxxxxxxxxx wrote:
> > >
> > > Ben and Wesley,
> > >
> > > In these drawings, I was consistant with 802.3's usual notational
> > > conventions
> > > which show bit fields with the LSB/first transmitted bit on the left. For
> > > instance,
> > > see Figure 3-1. If you search the base standard for LSB, you will find that
> > > almost
> > > all* figures and binary bit representations (see 22.2.3.2.1 for an example)
> > > are
> > > shown with least significant bit on the left while hex representations of
> > > fields
> > > are shown in the normal order. I didn't make it that way but at this point
> > > we
> > > should not change it.
> > >
> > > Pat
> > >
> > > *The only deviant I found was 23-7 but the code tables for 23 (see Annex
> > > 23A)
> > > follow the convention.
> > >
> > > -----Original Message-----
> > > From: Wesley Lee [mailto:wlee@xxxxxxxxxx]
> > > Sent: Monday, October 09, 2000 12:33 PM
> > > To: stds-802-3-hssg@xxxxxxxx; bbrown@xxxxxxxx
> > > Subject: Re: 64B/66B Control Codes Mapping & Bit Order
> > >
> > > Ben,
> > >
> > > I'd support you in recommending to flip the order of bits in Fig 49-5 as
> > > you suggest in the following. Table 49-1 shows bits msb->lsb
> > > but fig 49-5 shows the opposite so one can't simply stuff the
> > > control codes in table 49-1 into fig 49-5.
> > >
> > > Regards,
> > > -Wesley Lee
> > >
> > > ben brown wrote:
> > > [snip]
> > > Hope this helps. Although it might be too late to make
> > > a dramatic change to this table at this point (simply
> > > because people are beginning to be familiar with it),
> > > I would be eager to recommend to the clause editor that
> > > this table be redrawn where the first column changes the
> > > order of the bytes from D0...D7 to D7...D0. Then, move
> > > the SYNC column to the far left and reverse the order of
> > > those bits (DATA = 10, CONTROL = 01). The Block Payload
> > > column could then be re-ordered to show D7...D0 for the
> > > Data Block Format and C7...C0, Type Field for Control
> > > Block Format. This way, the 66-bit field is laid out
> > > in front of you with [65] (the msb) on the left and [0]
> > > (the lsb) on the right, the way many of us are most
> > > familiar with looking at numbers or fields. Also, the
> > > hexadecimal equivalents of fields, which are written with
> > > msn (most significant nibble) on the left and lsn on
> > > the right, could be simply expanded into their binary
> > > equivalents without having to perform a mental bit swap
> > > to match the table.
> > >
> > > --
> > > ==================================================================
> > > Lucent Microelectronics Group - West
> > > 1381 McCarthy Blvd, Miltpitas, CA 95035
> > > Work: 408-952-8822 FAX : 408-952-8887 wlee@xxxxxxxxxx
> > > ==================================================================
> >
> > --
> > -----------------------------------------
> > Benjamin Brown
> > AMCC
> > 2 Commerce Park West
> > Suite 104
> > Bedford NH 03110
> > 603-641-9837 - Work
> > 603-491-0296 - Cell
> > 603-798-4115 - Home
> > bbrown@xxxxxxxx
> > -----------------------------------------
--
-----------------------------------------
Benjamin Brown
AMCC
2 Commerce Park West
Suite 104
Bedford NH 03110
603-641-9837 - Work
603-491-0296 - Cell
603-798-4115 - Home
bbrown@xxxxxxxx
-----------------------------------------