Right underneath the 'GMCH' you can find 82801, the 'ICH' = 'I/O Controller Hub' . This part of the chipset talks to all the PCI-devices over the PCI bus, to the EIDE hard drives over either ATA33 or an ATA66 interface, to external devices over the USB, to a low priced modem/audio-codec via AC97 and finally to the 'FWH' = 'Firmware Hub'. The ICH is the place where all the outside communications run together, forwarded to main memory, the CPU or the integrated graphics controller over this new 266 Mb/s bus.
The FWH - 82802
Behind the name 'FWH' = 'Firmware Hub' you'll find a chip that's not much else than a 4 Mbit EEPROM plus a tiny bit of active silicon. The EEPROM contains the motherboard and graphics BIOS and the active silicon is a random number generator. Intel is currently making a big mystery out of this random number generator, supposedly because there isn't any software available yet. We all may guess what this little thing is supposed to be for.
The Different Flavors Of The Intel 810-Chipset
Intel sells the 810 in three different versions, as shown in the graph below:
As you can see, you get to three different flavors by mixing GMCH0/GMCH and ICH0/ICH with each other in different combinations. GMCH0 does not support the external display cache and is thus supposed to be slower in 3D-applications. GMCH can be equipped with external display cache, but it doesn't have to. ICH0 supports only 4 PCI slots and only ATA33, whilst ICH can run with up to 6 PCI slots and use ATA66 to talk to EIDE hard disks.
This is the cheapest version for super low cost motherboards. It comes at $23, can't be equipped with display cache, the EIDE hard drive can only use ATA33 and the motherboard can be smaller, because there is no sense in more than 4 PCI slots.
This version costs $27. There's also no option for a display cache, but you get the full-blown I/O-hub with support of up to 6 PCI slots and ATA66 for the EIDE drive.
- i810 - DC100
Don't ask me what the 'DC100' stands for, but this version costs $30 and it's the 'high end'-version of i810. The only difference to the normal i810 is the option for a display cache, which is supposed to speed up 3D-graphics.