Please refer to this link.There are two different EOS firmware images list at the link above: an 82000854 firmware image and an 82000684 firmware image. Which firmware should you use to update the firmware on your older model Portserver TS8 or Portserver TS16 product?
One way is to compare the 50mil part number from the underside of the Portserver TS chassis with the information at the link above. If you dont have access to the part number of the TS but can Telnet into the product to access the CommandLine Interface, there's a way to determine this via the "show memstats" command.
Access the Portserver TS commandline, either by being connected directly to one of the ports with a terminal, or via telnet/ssh to the IP address of the unit. Once logged in as root, issue the following command:show memstats
show memstats gives you general information about memory usage. If the "Heap size" statistic is on the order of 13+ or so MB, the product has 4MB flash/16MB RAM, and would use the part number 82000684 EOS firmware image. If the number listed is more on the order of 1-2MB, the product is a 2MB flash/4MB ram unit, and would require use of the smaller the 82000854 EOS firmware image.