The KT333: How VIA met the challenge
VIA's KT333 chipset will look awfully familiar to most of us. Essentially, VIA has just modified the KT266A north bridge chip in order to support DDR333 memory. The pinouts on the KT333's north and south bridge chips follow VIA's V-Map standard, so the KT333 north bridge is obstensibly a drop-in replacement for the KT266 or KT266A. (Heck, it's theroetically pin-compatible with the P4X266A, for whatever that's worth.) Like those chipsets, the KT333 north bridge chip can be paired up with one of several different south bridge chips.
The newest of those south bridge chips, and the one most likely to be paired with the KT333 north bridge, is the VT8233A. This sexy, sexy name describes the latest revision of the standard VIA I/O controller chip. The VT8233A's revamped hard drive controller now supports ATA/133 transfer modes and will work with hard drives larger than 137GB.
The KT333 north bridge chip
The south bridge chip with ATA/133 support
Beyond that, there's not really too much to report, except this: VIA's KT266A chipset is very fast, as we have noted in previous reviews. The memory controller in the KT266A was a breakthrough for VIA, whose past memory controllers weren't always impressive performers. In making the KT266A's memory controller as fast as it is, VIA added deep pipelines and lots of buffering. This foundation may prove pivotal in the KT333, where deep buffers might help the KT333 north bridge chip act as an effective liaison between 333MHz memory and a 266MHz processor bus.
As for the problem with the JEDEC DDR333 spec, VIA is doing several things to calm the minds of those on the bleeding edge. The JEDEC spec sheet for DDR333 components (presumably like the KT333) is final, so buying a KT333 while we wait probably isn't too risky. What we're waiting on is the DIMM spec, which is in verification now. To augment JEDEC's efforts, VIA has its own DDR RAM validation efforts, which I expect will produce some recommendations for DIMM purchases.
A block diagram of the KT333 chipset
