Subject: Re: 100baseT ethernet card questions
To: None <>
From: Hal Murray <>
List: current-users
Date: 12/07/1998 18:49:54
> Doesn't seem to be very compatible.  I also hate it when vendors change
> PHY's without bumping at least a revision level or something.  Basically,
> you should be able to specify a part and know what you're getting; I expect
> a vendor to change part numbers if they're changing hardware.

It's a complicated area.  I don't think there are any easy solutions.

If you buy in high volumes you get a lot more information, help, 
and leverage. 

If a vendor is going to stop making a chip, they usually warn all 
their big customers.  The typical deal is something like "We will 
fill all orders received by xxx".  So if you have a board that uses 
that chip you can buy a pile of them and put them in your stockroom.  
"End of life purchase" is the buzz word.

You might buy a few extras as insurance in case business gets good.  
If business gets real real good, you will probably have time to redesign 
and retest that board. 

Chip vendors often change their designs.  If it is just a minor change 
they probably don't tell anybody.  For example, a chip might get 
a bit faster over the years as they tune the production line.  If 
might get a lot faster all of a sudden when they shrink the mask 
set so they get more chips per wafer.  If it still meets the original 
specs and passes the same tests why bother changing the part number? 

Usually, if they change the logic of a complicated chip in any "interesting" 
way, including bug fixes, they will change the version number and/or 
part number. 

There is a tradeoff on changing the version number or part number 
on a chip or the board that uses it.  Everybody downstream has to 
change their paperwork and probably retest their design.  Testing 
can be very expensive.  (So is a problem that slips through testing.) 

So if you don't change anything "interesting" and nobody can tell 
the difference you waste a lot of time/effort/money.  On the other 
hand, if you botch it and some change that shouldn't get noticed 
turns out to cause serious problems everybody you should have warned 
is going to be annoyed at you.  (Stronger words are sometimes appropriate.  
Some people remember when they get burned and take their business 

It would be interesting to find out how much testing they did with 
this "compatible" chip.

These are my opinions, not necessarily my employers.