Heh! When I saw the subject line, I thought you wanted to upgrade a _physical_ -11/40 to an -11/45. ('Step 1. Sell the -11/40. Step 2. Buy an -11/45.' :-) Why on earth would an organization have such a thing? :-) Heh. If said techie knows about the two, he's probably pretty senior (i.e. eligible for Social Security :-), and thus elegible for first class... :-) Who the *&%^&*(%& is still writing code under V6?! And how do you all get the bits in and out? (I run mine under Ersatz-11, which has this nice device which allows it to read files off the host file system; transfering stuff back and forth is a snap, I do all my editing with Epsilon on my Windoze box, 'cause I'm too lazy to bring up the V6 Emacs I have.) Not that I know of. You're asking _us_? Some larger applications will only run on an split-I-D machine, is about the only reason I can think of. Oh, also, the floating point instructions on the /45 are the only kind understood by V6; the C compiler doesn't emit the ones the /40 provides. Any floating point code run on the /40, the instructions are simulated by a trap handler (by way of the OS, which has to handle it and reflect it to the user process). I.e. very slow. See above. Any V6 disk pack can be read/mounted on any V6 machine. Any binaries (the OS, or user commands) for the -11/40 will run on the -/45. (Which is why the V6 dist includes binaries for /40 versions of the OS only.) To make use of the /45, you need a different copy of the OS binary, built from a slightly different set of modules. (Replace m40.s with m45.s; and you will need to re-asssemble l.s, prepending it with data.s.) Both variants can live on the same pack, under different filenames; select the right one at boot time. 256KB is all you can have. Neither SIMH nor Ersatz-11 support the Able ENABLE: http://gunkies.org/wiki/Able_ENABLE which is what you need to have more than 256KB on a UNIBUS -11. More importantly, look at the 'run' file in /usr/sys, which has commented out lines to build the OS image for /45-/70 class machines. This is actually of limited utility, since a V6 file system is restricted to 65K blocks _max_. So a disk with 350K blocks (like an RP06), you'll have to split it into like 5 partitions to use it all. Heh. Spun up my v6, and did "file * | grep separate" in /bin and /usr/bin, and then recalled that V6 was distributed in a form suitable for a /40. So, null set. Did the same thing on /bin from the MIT V6+ system, and got: a68: separate I&D executable not stripped a86: separate I&D executable not stripped bteco: separate I&D executable not stripped c86: separate I&D executable not stripped e: separate I&D executable not stripped emacs: separate I&D executable not stripped lisp: separate I&D executable not stripped mail: separate I&D executable not stripped ndd: separate I&D executable not stripped s: separate I&D executable not stripped send: separate I&D executable not stripped teco: separate I&D executable not stripped No idea what the difference is between 'teco' and 'bteco', what 's/send' do, etc. No; like I said, you can have two different OS binaries on the disk, and select which one you boot. Build a system with both, and then copy the files? I'd use 'tar' (I have a V6 tar, but it uses a modified OS with the smdate() call added back in) to do the moving (which would retain the last-write dates); 'tp' or 'stp' would also work. The hack _I_ used on simulated systems was to expand the file that held the 'disk pack', mount it as a different kind of pack (RL or RP), and then go in and hand-patch the disk size in the root block with 'db', then 'icheck -s' to re-build the free list. Note: this won't give you more inodes, so you may run out, but the usual inode allocation is pretty generous. Noel PS: Speaking of the last write dates, I have versions of mv/mvall, cp/cpall, ln, chmod etc which retain them (using smdate()). If there's an actual community of people using V6, I should upload all the stuff I have. Although it might be good to establish some central location for exchange of V6 code. However, I don't and won't (don't even ask) use GitHub or any similar modern thing.