Dick Smith System 80

Hi! I think someone on this list is a System 80 expert, and I am hoping I can find them. :) I just picked up a System 80 with expansion box and disk drives, but I'm having some trouble. When I power it up I either get gibberish on the screen (the usual stuff you get before the ready signal) that doesn't go away, or, when I switch the box off,I just jump to BASIC. This happens with or without a disk in the drive. I tried another System 80, and that one didn't seem to notice the expansion box at all - it always went into BASIC, whether or not I had the box switched on. None of the manuals seemed to have anything useful to say, but I suspect that either I am being really stupid and failing to do something basic, or something is broken somewhere. Any ideas? Thanks heaps, Adam.