Working from left to right. First picture contains the following:
* Echelon FTT-10A (model 50051R) is a twisted pair transceiver
* Some miscellaneous chip (can't tell due to blur)
* Xilinx controller of some kind (can't tell due to blur)
* ST Semicondumer Flash chip
* Echelon 803P-0001 chip is probably a RAM chip of some kind that's used in combination with the transceiver. Echelon stuff is certainly related to the yellow/orange port on the left
* Some kind of PLCC, possibly/probably a BIOS
* Texas Instrument controller of some kind (can't tell due to blur)
* (below the TI chip) Some miscellaneous chip, probably RAM (can't tell due to blur)
* (below the ST chip) Some miscellaneous chip (can't tell due to blur)
Second picture contains the following:
* (2) Texas Instrument LV165A shift register chips
* (2) Texas Instrument TL16C7528 serial (UART) controllers with 64-byte FIFOs. Think of these as your classic "16550 UART/serial ports"
* (below TI chip) Some miscellaneous chip (can't tell; don't care)
* Intel 82551ER 10/100mbit Ethernet controller with integrated PHY
* "Large green HSF" is, as myself and others have said, almost certainly the main CPU and might be a SOC of some kind (not sure)
Third/fourth picture contains the following:
* Miscellaneous chips that are probably shift registers or other simple logic chips, possibly voltage-related oo
* (2) Maxim Integrated MAX3241CWI RS232 serial controllers
* (Not a chip) Murata-PS NMD050505SC DC/DC power converter
Are the two silver ports at the bottom of the board USB ports? It's hard for me to tell. If so, that makes me wonder where the USB controller is, unless it's part of the SOC. It could be on the opposite side of the PCB too. If they aren't USB ports, okay!
Hope this helps.--
Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer.