PortMaster 3 woes
When I bought the PortMaster 3 from eBay, there was one huge oversight. The model I bought was a PM3A-1E. This designation indicates that there’s a single E1 port. The Adtran TSU 600 only accepts a T1 connection. I have no idea how this major detail slipped from me. I assumed that the T1/E1 labelling on the diagram provided by the PDF I referenced in the previous post meant that either a T1 or E1 connection could be used. No matter, I bought a T1 motherboard along with an additional T1 card (which could be used with the board I already have) and the required modems which my unit didn’t ship with. To be fair; I wasn’t expecting modems and waited until it arrived before moving forward.
That’s a slight delay and not one to kick up much of a fuss about. However, the real issue is that it’s seemingly impossible to factory restore the unit due to the requirement of logging in to the unit to perform the operation…
There’s a lone jumper on the board (J1) which I was hopeful would allow the NVRAM to be reset. Unfortunately, this only serves to reflash the Ethernet controller. Okay, so how does one go about solving this issue? In my case, I think it will be easiest to desolder the NVRAM and hope that it can be either erased and the unit will allow for flashing from scratch or that the data on there can be manipulated to bypass the password. I have no idea how the data is arranged, short of a hint from the manuals that there are at least four, possibly eight, partitions, with the third one containing the configuration data. The NVRAM in use is an AMD AM29F040-120JC. Two of these chips hold a combined total of 1MiB. Each chip is split into eight 64K sectors. It may mean that if there are eight partitions, they’re split into 128K (two sectors on chip).
It may be necessary to also dump the PROM, though I’d rather not due to there being a nice factory sticker which would be rude to ruin. The operating system (ComOS) may be entirely proprietary or based on Linux. Given that this was made in 1996/1997, it may be the former. The hope is that if the data isn’t easily readable (i.e. the file system isn’t usable or encrypted) that the chips can be erased and no harm is done. I’ll make another update as soon as I either fail or succeed with my attempt to reflash the firmware. I need to get a universal programmer, plus a PLCC32 adapter for it, a finer conical point for the soldering iron, and a better-suited nozzle for the hot air rework station.
In any case, this will be a fun learning experience.