PC/AT memory boards

I've got an old genuine IBM AT (8 MHz) that has a couple of 16bit mystery boards in it... 1) Marked 55x3543, google says 0.5 to 3 MB board. It has a 16450 on it, a total of 12 30 pin simms, a male DB9 (okay, I guess it's a DE9) and a female DB25. I assumed it was a serial port and parallel port but it doesn't show up as such in the machine. Also since these appear to be 256K simms I expected the machine to boot with 2MB of RAM or more but it only came up as 1 MB. I'm suspecting it's configured wrong or there's a conflict but of course I don't have any docs... anyone? 2) Another memory board, 18 256Kbit chips, marked EV159 and has a big EVEREX chip on it. Google says 3 MB expansion board, same questions. I assume this motherboard has 512K on it, so... this board might be okay but I'd like to know what the switch settings are in case I decide to add memory to it (anyone know a cheap source of 41256s? Any help (docs especially) would be appreciated.... Gordon Zaft zaft(a)azstarnet.com