But it doesn't add I/D to a machine without it, though, right? (I tried looking for Enable documentation online, couldn't find any. Does anyone know of any?) I recall at MIT we had a board we added to our 11/45 which added a cache, and the ability to have more than 256KB of memory, but I am unable to remember much more about it (e.g. who made it, or what it was called) - it must have been one of these. I recall we had to set up the various memory maps inside the CPU to permanently point to various ranges of UNIBUS address space (so that, e.g. User I space was assigned 400000-577777), and then the memory map inside the board mapped those out to the full 4MB space; the code changes were (IIRC) restricted to m45.s; for the rest of the code, we just redefined UISA0 to point to the one on the added board, etc. And the board had a UNIBUS map to allow UNIBUS devices access to all of real memory, just like on an 11/70. I honestly don't recall much about how the board we had at MIT worked, but i) the memory was not on the board itself, and ii) there had to be some kind of special arrangements for the memory, since the stock UNIBUS only has 18 bits of address space. IIRC, the thing we had could use standard Extended UNIBUS memory cards. I don't recall how the mapping board got access to the memory - whether the whole works came with a small custom backplane which one stuck between the CPU and the rest of the system, and into which the new board and the EUB memory got plugged, or what. I had _thought_ it somehow used the FastBUS provision in the 11/45 backplane for high-speed memory (since with the board in, the machine had a basic instruction time of 300nsec if you hit the cache, just like an 11/70), and plugged in there somewhere, but maybe not, since apparently this board you have is for a /34? Or maybe there were two different models, one for the /45 and one for the /34? Since I doubt it adds I/D to machines that don't already have it, I would guess no. Unless somehow one can use overlays, etc, to fit 2.11 into 56KB of address space (note, not 'memory'). That's where I'd go. I do have that MIT V6 Unix with TCP/IP, where the TCP is almost entirely in user space (only incoming packet demux, etc is in the kernel), and I have found backup tapes for it, which are off at an old tape specialist being read, and the interim reports on readability are good, but until that happens, I'm not sure we'll be seeing TCP/IP on non-split-I/D machines. Noel