HP 9820A

I was dropping off some rubbish today at the local council dump, and noticed an old HP machine in the trailer next to me. I didn't even say anything, I just stopped and stared at it and the guy asked if I wanted it. When I said yeah, he replied with "shame you weren't a few minutes earlier, I just chucked two others in the recycling bin and all the manuals and tapes/cards are in the pit." Turned out to be an HP 9820A, and I managed to get the other 9820A and a 9810A out of the recycling bin without anyone noticing. Unfortunately couldn't retrieve anything else. Just wondering if there is anything in particular to watch out for when powering up one of these for the first time other than normal power supply checks? I (obviously) don't know much about these machines at all, but I'm particularly mystified about how the built in card reader worked (is it magnetic?).. Could it be written to as well? Cheers, Chris