Ben Pope said:
Since a particular core, be it R300, R350, R420 or whatever, can support
various configurations from budget to top-of-the-line it makes sense for
them to fab only one core and discontinue all products based on the old
core. This is very similar to what nVidia are doing.
Normally I'd agree with you, but just to throw a spanner in the works,
ATI have deviated from this with their current cards. Whilst the 9500
and 9700 cards were based on exactly the same core, the 9800 and 9600
cards are not, requiring separate cores to be produced for each.
From what I've read, it appears that the 9500 wasn't a very good move
for ATI from a business perspective. It used the relatively expensive
(to produce) R300 core, yet sold at a very low price point compared to
the 9700 cards, squeezing their margins considerably.
With the 9600s, they have produced the RV350 core, which is very similar
to the R300, save for a few minor technical differences, but crucially
is a .13 micron part. This allows them to squeeze more onto a single
silicon wafer compared to the R350, thus bringing costs down on this
core, and keeping the margins on the 9600 cards up.
I strongly suspect that ATI are also using the RV350 core as a means of
"testing the water" with .13 micron, especially given the problems
NVidia experienced with it. Once they're happy with the process,
they'll begin shifting their top-end cores over to it, which I believe
will start happening from Loki onwards.