The PM133 northbridge is VIA's model VT8605. This is a full-featured northbridge with the following specs. We've trimmed the list to cover just the important features:

• Slot 1 and Socket 370 processor support (Pentium III/Celeron/Cyrix III, etc.)
• 66/100/133MHz FSB speeds
• 660/100/133 SDRAM and VCM memory speeds
• 64-bit memory bus
• Supports three DIMMs with up to 1.5GB of memory
• Integrated S3 Savage4 2D/3D video
• AGP 4X slot (overrides internal video)

On the CPU support side, the PM133 supports a wide variety of processors and can be built into Slot1 and Socket 370 motherboards. On the memory side, VIA outdoes Intel with 1.5GB of memory support, as opposed to the i815 chipset's 512MB support. Also, the PM133 chipset supports Virtual Channel Memory (VCM). An external AGP slot lets you upgrade your video but also disables the internal video.