The machine of the DSSR/RTS group at MIT-LCS, Steve Ward's group (an -11/70 running roughly PWB1) had an implementation of a form of Perquackey: https://en.wikipedia.org/wiki/Perquackey that was a multi-player game; I'm pretty sure there was a process per player, and they communicated, I'm pretty sure, through pipes, not files - there was certainly no IPC in that system. IIIRC, the way it worked was that there was a parent process, and it spawned a child process for each terminal that was playing, and the children could all communicate through pipes. (They had to communicate because in that version, all the players shared a single set of dice, and once one person had played a word, the other players couldn't play that word. So speed was important in playing; people got really addicted to it.) Alas, although their machine was very similar to CSR's (although ours was an -11/45 with an Able ENABLE and a lot of memory, making it a lot more like a /70), and we shared most code between the machines, and I have a full dump of the CSR machine, we apparently didn't have any of the games on the CSR machine, so I can't look at the source to confirm exactly how it worked. Noel