VIA's PT894
PT894 explicitly pairs a PCI Express only core bridge with VT8251 for its I/O processing. Otherwise, it's very similar to PT880 Pro.
| VIA's PT894 Core Logic | |
| CPU Support | All Intel Pentium 4 LGA775 Processors |
| Northbridge | VIA PT894 |
| Memory Support | Dual-channel, up to DDR400 or DDR2-667 |
| AGP | None |
| PEG16X | Support for one slot, 16X, 0.8V |
| Southbridge | VIA's VT8251 |
| Audio | VIA Vinyl Audio supporting discrete ASIC and AC'97 interfaces |
| PCI | 7 x 32-bit 33MHz PCI 2.1 slot controller |
| PCI Express | 20 lanes in total on the northbridge (16 for PEG, 2 exposed for peripherals), 2 lanes on VT8251 |
| IDE | VIA's DriveStation giving 4 drive support up to ATA133 |
| IDE RAID | Possible 0, 1, 0+1 and JBOD |
| SATA | 4 devices with command queueing from VT8251 |
| SATA RAID | Possible 0, 1, 0+1 and JBOD |
| Networking | 1000Mbit Ethernet MAC |
| USB | 8 ports USB2.0 HighSpeed |
| FireWire | None |
| Other I/O | MC'97, LPC, PS/2, Ultra V-Link |
PCI Express Only
VIA's core logic diagram for the PT894 is somewhat puzzling. Despite having 20 lanes in the bridge, it only appropriates 16 for graphics and 2 for I/O peripherals. I'm not entirely sure why since the spare 2 aren't used for anything else that I can see. There's no AGP support but you get full support for 166, 200 and 266MHz CPU-to-memory base clocks, DDR400 and DDR2-667 memory support and Ultra V-Link for hooking up to the VT8251.Positioned as a competitor to Intel's 925XE core logic in terms of features, but closer to 915P in terms of final board price to the end user, VIA want to bring a full gamut of features for users at a low price, citing cost as a main reason for the market's lack of platform pickup for this generation of Pentium 4. It's hard to argue in some respects.
It's nice to see VT8251 make a full appearance, locked to PT894 by VIA (although not on the reference platform!). It brings a fine disk controller with RAID support and command queueing, two lanes of PCI Express for peripherals, Gigabit Ethernet and fine audio support. Those are all things that the market expects in a modern Pentium 4 mainboard at the time of writing.
PT894 and PT880 Pro are both in mass production as I type this, having finished the sampling phase some time ago. Board makers should have boards ready in due course and VIA's list of AIB partners is numerous and encompasses most of the usual suspects. A full and official list will be forthcoming shortly, I'd imagine.
I was lucky enough to have the reference boards early, which affords us opportunities in terms of platform evaluation, but with VIA's reference boards notoriously hard to work with, it wasn't so lucky in some respects.
