Xerox 820 lives!

Greetings to all -- About a year ago, Joe Rigdon very kindly gave me a number of old machines (thanks, Joe!), among them a Xerox 820. At the time he gave it to me, the unit didn't power up, but today I finally found the time to give it a second look. After I reconnected a loose lead inside the box it came to life! This is my only machine with 8" disk drives, so I'm interested in finding a good use for it. I could use some help from the list members, though. I found *no* technical data via Google, and have *no* real docs for this beast. After poking at the 820 for a bit, here's where I'm at: --> The "B" drive is faulty. Disk initialization fails, and it will not consistently read disks created on the "A" drive. Any pointers on replacement drives? Even if a thorough cleaning revives this drive, I'd like to obtain a spare. --> Assuming I can't revive the "B" drive or find a replacement, how can I duplicate diskettes? The CP/M utilities all seem to want two drives in order to do their job. --> Two of the boot diskettes which I have boot up a pretty normal looking version of CP/M 2.2, with a normal "A>" prompt, but another diskette displays the following upon boot: "Good Day! ZCPR 2.04 SYSTEM READY" and the prompt is "A0>" (obviously user group 0). What is this "ZCPR"? --> Some of the utilities on the boot diskettes (FMT, for example) refer to hard disk drives. What's involved in attaching a hard drive to this system? --> The flimsy "User Manual" which I have states that the RS232 port may be configured to attach to a terminal or to a modem. How? --> Lastly, does anyone have any documentation on this thing? If you can part with it, I'd be glad to pay a fair price. Thanks in advance for any help you can provide. Although this system doesn't appear to be special or unique, it does seem to be a sort of nice, friendly critter, and I'd like to put it into use. Later -- Glen 0/0 If I am not for myself, then who will be for me? And if not now, when? -- Pirkei Avot