Yeah, but Clem's note reinforces my vague memory that the XGP-11 was an -11/20. I wish we had a picture of the Knight TV system (the system, not a terminal). It's a extremely significant system - I believe it my have been the first bit-mapped computer display system ever; and thus the prototype, in some sense, for the display of every single personal compupter (including phones) now extant - and so there _ought_ to be a photo of it. But looking online for a while, I can turn up almost nothing about it! (I guess we should do a page about it on the CHWiki...) (Repeat my prior grump about how the AI Lab did all sorts of ground-breaking stuff, because it was just 'tools', and not their main research focus, it's hard to find out about a lot of it, e.g. the inter-ITS network file system.) But if you can find an image, even a low-res picture of that end of the AI Lab machine room, we can tell what model the TV-11 is - early 11's had inteagrated front panels, which are different for every model: http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/PDP-11_Models.html so you don't even need to be able to read anything to tell a /20 from a /10. It was in a dual (I think - maybe triple, it's been a looooooong time :-) rack which IIRC was along the side wall (i.e. the short building side) next to the AI KA10 (which was sort of along the long wall, up in the corner). I don't know if the XGP-11 code is still extant (my copy of the ITS filesystem is offline right at the moment), but even if we look at the code, I'm not sure we could tell; there are some _very minor_ programming differences between the /20 and /10 (e.g. V bit on SWAB) - see the table at thd end of the PDP-11 Architecture Handbook - but I'd be aurprised if the code used any. Surely there has to be _some_ picture of the machine room which shows it, even if in the background. Try RG, too. Noel