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Implementation vs. Standard

	a while back I sent a message about PUDI(/INVALID/) and decoder
placement.  In your reply you said:
Rich Taborek wrote:
> Justin,
> The Sync state machine is written to operate in the 10B domain as is the
> Deskew state machine.
> The 10GBASE-X PCS does not mandate the location and number of decoders
> in an implementation. The PCS Sync and Receive state machine structure
> is virtually identical to that of the 1000BASE-X PHY. The DECODE
> function can be located elsewhere, but I don't view such a change as
> being more or less "correct" than it's current location.
> As to your second point, Invalid represent a superset of invalid
> code-groups and running disparity errors. Therefore, running disparity
> error is not a suitable replacement for Invalid.
> Best Regards,
> Rich

I am new to the standards based design, so I dont quite understand where
the line between standard and implementation is drawn.

It was my understanding from the spec. that the "PCS shall implement its
Transmit process as depicted in Figure 48..., including compliance with
the associated state variables as specified in 48..."  means, I have to
put the decoder where specified, and not before the deskew and sync
state machines.  Now I know I could design a circuit that behaves the
same as the standard but place the decoder before the deskew and sync,
but is this still compliant?  Can I still select Yes in the PICS to
meeting the requirements of the State Machines?


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