[ethmac] Remarks/Questions about the new Rx/Tx diagrams

[nbase <nbase@nbase.com>]

19-Jul-00

   Hi,

   I just looked on the new diagram, and it look to me that few thing are
still need to be detarmine and maybe changed or defined accordingly.

Receive Machine :
1. do you really want first to do 4->8 and than all the work of SDF CRC etc
? why not stay in 4 bit (nibble) making thing very easy and 25M is also a
simple frequancy so there should be no problem there.

I would think that only in the last stage you gather the nibbles and write
them in word or more to the outside memorey/DMA .

keep in mind that while the preamble is 7 nibble long it might get
"shirnked" while it go through the network.

2. the issue of address recognition and DMA to different channel mean most
likely that you need some cpu interface to configure all kind of
information or did I missed something ?

also there should be a description of what each block receive and transmite
as otherwise it is not easy to "guess" what you want to do in all the
blocks. (this is also for the Transmite Machine).

Also there are still some arrow with no description so again it is hard to
guess what you expect them to do.

Tx Machine :
1. again as in the receive machine I suggest more detai as well as define
all arrow.

2. there is many generator block which I wonder what you need them for ? ,
for example jam , preambale , pad , I would think a simple 5 and D for
preamble and maybe 0 for jam and padding and than the tx machine contor the
mux which to use.

3. I wonder also what is this 8 bit of pause you pass from the Rx to the Tx
I would think a 1 bit signla of stop/start is enough ?

One more thing your comment about "i'm still trying to understand the
details of the receive operations for half and full duplex, as you can see
the signals in diagrams are not", in the receive sice I belive the easiest
way is to desing it for half duplex and than and gate the collision signal
with the full dupolex signla which is a management signal and thus while
working in full duplex is as if there is no collision so there is no need
to filter packet ondle partition case and so on. (and this also bring the
question where is the partition machine ? , of course if you think to
support only full duplex than this machine is not needed).

have a nice day

   Illan