While I'm investigating the legacy of the UNIX syscalls, I might as well go into the later versions. 2nd Edition UNIX kept all the syscalls of 1st Edition, and added these: 34 hog lower process priority, becomes nice() 35 sleep sleep() 36 sync sync() 37 kill kill() 38 getcsw reads console switches: this goes away in 7th Edition 3rd Edition UNIX kept all the syscalls of 2nd Edition, and added these: 39 boot reboot the system, becomes reboot() 40 fpe catch floting point errors, becomes signal(SIGFPE, ...) 41 dup dup() 42 pipe pipe() 43 times get process time details, becomes getrusage() Note pipe() appears in the 3rd Edition, which was still in assembly. 4th Edition UNIX is the first kernel written in C. We start to see changes: 14 mknod was mkdir(), now can make directories and device files 34 nice was hog() 20 tell goes away, as seek() does the same job 44 profil profil() 45 tiu interface to Spider digital switching network: goes away 46 setgid setgid() 47 getgid getgid() 48 signal signal() It's interesting to note that signal() appears, but the existing signal-like syscalls do not disappear just yet, although tell() does go away. It's also to note that seek() has the usual 0=SEEK_SET, 1=SEEK_CUR, 2=SEEK_END, but there are also 3, 4, 5 which mean the same except that offsets are multiplied by 512 bytes. This is to do long seeks on block devices. Earlier UNIX kernels automatically multiplied offsets on block devices by 512, but now the task of doing this has been shifted to the process. In 5th Edition, we see some more changes: 20 getpid getpid(), fills the slot vacated by tell() 26 quit goes away to be replaced with signal(SIGQUIT, ...) 27 intr goes away to be replaced with signal(SIGINT, ...) 29 cemt goes away to be replaced with signal(SIGEMT, ...) 33 ilgins goes away to be replaced with signal(SIGILL, ...) 39 boot goes away 40 fpe goes away to be replaced with signal(SIGFPE, ...) 45 tiu goes away 6th Edition has few changes over 5th Edition: 26 ptrace ptrace(), fills the slot vacated by quit() 30 smdate becomes inoperative 7th Edition has some significant changes over 6th Edition: 27 alarm alarm(), fills the slot vacated by intr() 29 pause pause(), fills the slot vacated by cemt() 30 utime utime(), replaces the missing smdate() 33 access access(), fills the slot vacated by ilgins() 35 ftime get date and time, later becomes gettimeofday() 38 getcsw goes away 39 setpgrp setpgrp(), but not yet implemented, i.e. reserved slot 49 unused 50 unused 51 sysacct turn accounting off/on 52 sysphys set user physical addresses 53 syslock lock user in core 54 ioctl ioctl() 55 unused 56 mpxchan create mpx communications channel 57 unused 58 unused 59 exece execve(), note that existing syscall 11 exec() has no envp[] 60 umask umask() 61 chroot chroot() Note that 35 sleep() is now gone, as its functionality can be simulated with 27 alarm(). Cheers, Warren