The mainboard has four big integrated circuits worth mentioning. Three of their datasheets are attached to this guide for reference.

The Micrel "Centaur" KSZ8695PX in the upper-left is an ARM-based system-on-chip. Specifically, it features a single 166MHz 32-bit ARM9 core, support for up to 64MB of combined RAM and ROM, and built-in ethernet and PCI interfaces.

The datasheet makes it apparent that this chip was intended to use that PCI interface with a wireless networking card or chipset for use in a wireless router or something similar.

The big chip off to the right is an NEC D720101GJ, which is normally used on standalone PCI USB cards like the Belkin F5U220, indicating that the chip is part of a PCI-driven USB chipset built right into the mainboard. The chip supports up to 6 USB 2.0 ports (from what I can tell by the features of cards using it), but only five are used.

The chip on the bottom left is an Excel Semiconductor ES29LV160D 16Mbit (2MB) flash memory module. Supposedly, this stores some kind of modified Linux; I contacted Belkin asking about obtaining firmware source code, but haven't received a response yet...

Last but not least, in the bottom-middle, is a Winbond W9812G2GH SDRAM module. It has a capacity of "1,048,576 words x 4 banks x 32 bits", which - if I'm reading that right - translates to roughly 2MB of RAM (it's either 2MB divided into 4 banks or 4 banks of 2MB each; the datasheet's pretty vague).

When combined with the above-mentioned flash memory, that's a whopping 4MB of combined RAM and ROM - leaving about 60MB of wiggle room if someone wanted to solder on bigger memory modules.