I just tried disassembling the hex file. Unfortunately, the code protect bits are set (location 0x300008 is 0x00). This means that the ROM from 0x000800 to 0x007FFF will read as zero. And indeed, that entire space is filled with zero. So, I think we're missing much of the actual firmware.

Edit: And the reset vector begins with a branch to location 0x001ACA, which is all zeroes, so I'm pretty sure most of the firmware was not read out due to the code protection.