Re: [TUHS] Some notes on running UNIX v6 in 2015, using SimH and a healthy dose of documentation

I did a very similar exercise using the Ersatz11 simulator; I have a lot of stuff about the process here: http://www.chiappa.net/~jnc/tech/V6Unix.html It contains a number of items that you might find useful, e.g.: "V6 as distributed is strictly a 20th Century operating system. Literally. You can't set the date to anytime in the 21st century, for two reasons. First, the 'date' command only take a 2-digit year number. Second, even if you fix that, the ctime() library routine has a bug in it that makes it stop working in the closing months of 1999." Technically, a PDP-11 - there were a number of different PDP architectures: https://en.wikipedia.org/wiki/Programmed_Data_Processor is a decent listing of them; several (PDP-8, PDP-10, etc) were very popular and successful. A few things I noted in your first post: The only differences I could discover between the two are that in the Wellsch versions i) a Western Electric rights notice (which prints on booting) has been added to ken/main.c, and the Unix bootable images; and ii) the RK pack images do have, as you noted, the bootstrap in block 0. One should _never_ install a new shell version as '/bin/sh' until it has been run and tested for a while (for the exact reason you mention). Happily, in Unix, as far as the OS is concerned, the command interpreter is just another program, so it's trivial to name a new binary of the shell 'nsh' or something, and run that for a while to make sure it's working OK, before installing it as '/bin/sh'. Special files are UNIXisms for 'devices'. _All_ devices in Unix appear as 'special files' in the file system, usually (but not necessarily) in /dev - that location is a convention, not a requirment of the OS. Noel