On Mon, 27 Dec 2004 10:52:24 -0500, Patrick Finnegan <pat(a)computer-refuge.org> wrote: No. There are 1MB boards for the 11/24, but they are somewhat odd, IIRC. I have an 11/24 at home with a KT24 (M7134?) Physical Address eXtension (PAX) board that lets you put more than 256K of memory in the 11/24, giving it a slight edge over the 11/34, at least in terms of max memory (the 11/34C might be able to crunch numbers a bit faster). ISTR paying about $300 for it back in the late 1980s when I was trying to fiddle with 2BSD. If you don't have one, you are limited to 18 address bits. I found one advertised for $60 at this place -> http://www.smhelectronics.com/mclass.html I reasonably confident that the 11/24 and 11/44 used the same memory. For 256K boards, it should be the M8722 (MS11-MB). Grubbing around on http://www.pdp11.co.uk/search/modules.ehtml?name=ms11&submit=Search seems to suggest that the 1MB version is the M8743 (MS11-PB), but I don't have my hardware close at hand to check my own machines. Max is 4MB (as with any 22-bit address bus). ( see: http://www.village.org/pdp11/faq.pages/11model.html for general PDP-11 stuff ) In particular, the 11/750 has only one controller (unlike what's possible in the 11/78x line). There are 3 that I know of - the original one can only handle 256K boards (4116 DRAMs), the more common one can handle 1MB boards (4164 DRAMs, typically), and the newest one can handle, I _think_, two 4MB boards and enough 1MB boards to take the 11/750 up to 14MB total. There is a wire addition to the backplane to go from 2MB total to 8MB total (extra address line). I would expect some sort of similar change for the next bump, but I have never done it. the KA730 (11/730 and 11/725 CPU) does _not_ use Unibus memory... it has a set of dedicated 32-bit-wide memory slots on a custom CPU backplane, _next to_ the 16-bit Unibus slots. The max there, IIRC, is 5MB total memory. -ethan