[cctalk] looking for HP 1640B GPIB info

Hi all, I have a HP 1640B that I'm trying to get to work. However I can't find any information about it, and while the machine itself it straightforward enough (and I remember enough from when I was using it in my first dayjob) I can not find anything about how to use the GPIB interface that it has. The reason I'm interested is, we've finally managed to add GPIB support to the PDP2011-MINC fpga implementation, and I'd like to test against a different target than the relatively modern Philips/Fluke counter I'm now using. And the 1640B is the only other GPIB instrument I have... The HP doesn't seem to know the ID? command (that causes an error message on the screen). It does respond to a newline (the standard is-this-listener-present test that the MINC code implements), so at least something is working. Does anyone here have any docs on the HP 1640B? It'd be very helpful at least to know which GPIB commands are implemented. thanks in advance! Sytse