9-track tape drive: What is this?

I have absolutely no idea. It's plenty large, though... There's two boxes. One is the drive, the other is ??? The other is lighter than the drive. I'll drag it in here first. The front panel on the box says: HP 1000 A900 HEWLETT PACKARD. It appears to fit into a DEC rack... The back panel looks like this: +-----------------------------------------------------+ | ==== ==== ==== ==== === * === ==== ==== ==== ==== | | ==== ==== ==== ==== ==== ==== ==== ==== ==== ==== | | === ==== ==== ==== ==== ==== ==== ==== ==== === | | === ==== ==== ==== ==== ==== ==== ==== ==== === | | === ==== ==== ==== ==== ==== ==== ==== ==== === | | === ==== ==== ==== ==== ==== ==== ==== ==== === | | | | | | +-----+ +----+ | | | ST1 | | ST2| +----+ +------+ | | | | | | |ST3 | | ST4 | | | +-----+ +----+ +----+ * +------+ | | +-------------------------------------------------+ | | +--------------------OPEN SPOT--------------------+ | | SW1 PG1 DG1 SW2 PG2 | +-----------------------------------------------------+ Explanation: * means screw ==== means cooling vent. There are cards in a backplane behind these. Removing the screws allows access to the cards. ST1: Sticker one. says "Hewlett Packard" ST2: Sticker two. FCC rules stuff. ST3: Sticker three. Warranty sticker. ST4: Guess. says "Hewlett-packard. Product 2139A. Options O14. serial #. SW1: Switch. backup ena/dis PG1: Plug 1. 12-pin square plug. DG1: Diagram of the plug. EXT BAT + | MLT | +5M | -5 EXT BAT - | O1 | PON | +12 CMN | O2 | PFN | -12 SW2: on/off line PG2: Power Plug. That's all the back. Now for the drive! God, this is heavy! Too big to ascii, I'll have to describe it. It says "hp 7970E" Buttons a re LOAD, REWIND, ONLINE, RESET, 0, 1, 2, 3, OFF Connector is a small printer-plug looking thing (Like the plug on your printer, but smaller. I do have a scratch tape, how does one get the tape into these? Any info is appreciated.