There is an interesting paper that Dennis Ritchie and Dave Presotto wrote, “Interprocess Communication in the Ninth Edition Unix System” (https://www.bell-labs.com/usr/dmr/www/ipcpaper.html ). This appears to be an update of a paper that they wrote in 1985, “Interprocess Communication in the Eighth Edition Unix System”. This earlier paper is hard to find. Anybody on this list who has it on hand?